Beyonce Knowles, Gwyneth Paltrow, Jennifer Aniston, Michelle Williams, Reese Witherspoon, Kate Hudson, Cameron Diaz, Ellen DeGeneres, Julianne Moore, Chris Rock, Jamie Foxx, Olivia Munn, Selena Gomez, Paul Rudd, Jon Hamm, Jennifer Westfeldt, Will Ferrell, Sarah Silverman, Amy Poehler, Adam Scott, Rashida Jones, John Slattery, Jeremy Renner, Conan O’Brien, and others join together in the fight against gun control, in a new PSA for DemandaPlan.org.

The campaign, started by Mayors Against Illegal Guns, comes a week after the horrific massacre in Newtown and amid the polarizing debate rippling through the U.S. about gun violence and the Second Amendment.

Looking into the camera, they read through a list of some of the 31 similar attacks carried out in the US since Columbine in 1999.

‘Virginia Tech. Tucson. Aurora. Fort Hood. Oak Creek. Newtown. How many more?’ they ask. Watch the moving PSA here:

From the Hamptons to Hollywood, where were the starts this past week?

Kayne West and 50 Cent showed up to the first performance of Mike Tyson’s Spike Lee-directed one-man show “Mike Tyson: Undisputed Truth” this week. After the show, West and 50 Cent met backstage with Mike and Spike. The show will be running for a limited engagement at the Longacre Theater on Broadway from July 31-August 12.

Katie Holmes was spotted solo on the NYC streets this week! The 33-year-old actress looked cute in a denim jacket making her way back to her Big Apple apartment!

Recently single Kristen Stewart was spotted working out to keep her mind off of things at Gold’s Gym in Venice, California this week!

New York Yankee Alex Rodriquez was seen having lunch at the celebrity eatery 75 Main, while New York Knick Jason Kidd, Barbara Walters, Real Housewives Ramona Singer, Sonja Morgan and Heather Dubrow and actress Tika Sumpter and all dined at separate tables.

KEEP READING FOR MORE STAR SIGHTINGS THIS WEEK….

"Mud" Premiere - 65th Annual Cannes Film Festival

On June 6th, Camila Alves and Matthew McConaughey tied the knot!

Their beautiful wedding ceremony took place in their Austin, Texas home and they walked down the isle to John Mellencamp. The singer composed an original song based on a Bible verse that the newlyweds chose.

The wedding was far from traditional, being that the couple opted out of the ritual of cutting the cake and the first dance.

A few important guests were at the wedding including the couple’s two children, Levi and Vida. Also at the beautiful wedding were Woody Harrelson, Reese Witherspoon, Jim Toth and Meg Ryan.

The couple danced the night away in a spacious luxury tent and ate delicious Brazilian meats. A wedding guest said, “You could definitely tell Matthew was in love. It was a great night for everyone.”

Congrats, you (gorgeous) two!

Amanda Schwab/Starpix

Hollywood hotties Olivia Wilde and Emma Stone sandwich funnyguy Jimmy Fallon on the red carpet at the 15th Annual EIF REVLON Run/Walk for Women this week in the Big Apple! The two actresses were all smiles in their workout gear and seemed to be enjoying the NYC afternoon.

Host of BET’s “106 & Park,” Rocsi Diaz, was joined by celebrity pals Adrienne Bailon & Julissa Bermudez on the blue carpet at the 5 year anniversary celebration of MicahJesse.com, presented by NIVEA, at Canoe Studios. The TV personalities were joined by other famous faces in the media including Carrie Keagan, Phillip Bloch, Drita D’Avanzo (“Mob Wives”), Jonathan Cheban, and many many more!

After attending the LA Lakers v Denver Nuggets game at STAPLES Center this week, Kenny Hamilton cruised into boutique Hollywood nightclub AGENCY around 9:30 PM to celebrate his birthday amongst celebutantes and close friends with a special guest DJ set by Chris Lake. Spotted celebrating alongside Kenny were Rob Kardashian, Vinny Guadagnino, Brody Jenner, Zac Efron, and Ryan Cabrera.

Red hot former “Desperate Housewives” star Marcia Cross was spotted getting a Pink Smoothie gel manicure at Bellacures in Santa Monica this week.

The stars stepped out this week as they enjoyed a night of music with family and friends by attending the Coldplay concert. The lovely Ashley Tisdale was spotted entering The Hollywood Bowl venue with her parents while Gwen Stefani made her arrival in a bright pink jacket! Cameron Diaz was also in attendance.

Country cutie Taylor Swift was spotted leaving Neil Lane Jewelry store in LA this week. The beautiful songstress rocked pretty gold flats as she walked out of the store sporting some new bling.

KEEP READING FOR MORE STAR SIGHTINGS THIS WEEK!

PHOTO: Marion Curtis/Starpix

Julianne Moore was spotted at the New York City premiere of “Game Change.” The actress looked stunning supporting her latest film wearing a black and white gown to the event held at the Ziegfeld Theatre.

Natlie Portman and Benjamin Millepied were spotted at Il Covo restaurant this week enjoying a nice evening out. The Hollywood star and her man were joined by their 8-month-old son, Benjamin as they went to the Beverly Hills hot spot.

Gwyneth Paltrow was spotted at the Louis Vuitton/Marc Jacobs exhibition in Paris! Looking happy as always, she arrived at Les Arts Decoratifs as part of the Paris Fashion Week Autumn/Winter 2012 festivities.

It’s a family affair! Kate Hudson was spotted by her mom Goldie Hawn’s side helping out during the launch of her namesake foundation. Joined by fiance Matthew Bellamy, the actress looked amazing as she supported her mom, Goldie Hawn, at the at Annabels held kickoff of The Hawn Foundation.

She’s such a great wife! Khloe Kardashian was spotted supporting hubby Lamar Odom as his Dallas Mavericks took on the New York Knicks! She seemed to be enjoying the sporting event and was extremely happy after Lamars team won!

Katy Perry was spotted at the Miu Miu Ready-To-Wear Fall/Winter 2012 runway show in Paris this week! The songstress rocked a blue pony tail as she arrived at Conseil Economique as part of the Paris Fashion Week!

Kim Kardashian even looks good pumping gas! Kim K was spotted filling up the tank of her new Ferrari at Sherman Oaks looking gorgeous as always rockin’ some platform pumps!

FOR MORE STAR SIGHTINGS THIS WEEK, KEEP READING…

PHOTO: Amanda Schwab/Starpix

“From The Hamptons to Hollywood” we’ve got your celebrity round-up!

Supermodel Bar Refaeli (pictured above) was snapped leaving modeling industry expert Michael Flutie’s 5th Avenue office turned production site for E!’s new highly anticipated series, Scouted (premieres Monday, November 28th at 10pm). Bar will be appearing in an episode of the new modeling series.

Getting all pampered up ahead of her trip to Miami to visit boyfriend Scott Speer, Ashley Tisdale enjoyed a full day of getting all prettied up in LA this week! After getting her hair ‘did’ at the Byron and Tracey Salon, the actress later joined up with Hilary and Haylie Duff for a trip to a local nail parlor!

Dashin’ around NYC, Kim Kardashian was spotted making a stylish arrival back to her hotel this week after returning from her United Arab Emirates trip! The reality star strutted past paparazzi while meeting back up with the new hubby Kris Humphries.

Vanessa Minnillo was spotted on a little shopping spree in Studio City, CA. The beautiful brunette looked fashionable in a cute dress paired with a blazer as she excited the popular Belle Gray boutique.

Beyonce Knowles was spotted out and about in the “Big Apple”. The “Love on Top” songstress looked gorgeous in an all-black ensemble paired with blue heels, while entering an NYC building with her security.

Erika Christensen was spotted at the 2011 Scream Awards! Wearing Alexander McQueen, Christensen looked absolutely stunning.

Paris Hilton was all smiles during her visit to Disneyland in Paris this week! Having made the trip to the French capital the previous day, the heiress toured the theme park while stopping to pose for pictures alongside Cruella de Vil!

Jessica Biel was spotted out running errands in Studio City, CA earlier this week. Biel looked cool and casual in a white v-neck top with a printed skirt and black flats as she returned to her car to discover she’d received a parking ticket!

“True Blood” stud, Joe Manganiello showed off his hunky form on the Hawaii beaches. Manganiello was all smiles as he enjoyed some fun in the sun.

Emma Roberts was spotted at the Brazilian Style celebration at the Swarovski Crystallized Concept Store in NYC! The actress smiled for the paparazzi as she posed alongside actress Camila Alves as well as Gretchen Mol and Kelly Rutherford.

Hollywood hotties were among the many showing up for the SirusXM reopening of Studio 54 in New York City. Cameron Diaz joined sexy supermodels Bar Refaeli and Naomi Campbell for the retro nightlife scene recreation as the “One Night Only” party raged into the wee hours!

Teaming up to help launch a new mobile phone offering, 50 Cent and Zoe Saldana were the special celebrity guests at SIR Stage 37 in New York City this week. The actress and rapper posed arm-in-arm before parting ways so that 50 could perform at the DROID RAZR by Motorola and MOTOACTV launch event. Also at the event was Kelly Bensimon and Katrina Bowden.

The “Real Steel” hunk, Hugh Jackman was pumping some real steel at his New York City Gym before attending his Broadway press event held at Big Apple-based Pearl Studios.

Olivia Wilde was spotted on the city streets of NYC! The “House” hottie looked cute in boots, a skirt and leather jacket as she and a gal pal walked passed the on-hand paparazzi as they chatted away!

Jennifer Lopez stepped out to promote her Exclusive Fashion and Home Collection for Kohl’s Department stores this week. The American Idol judge wowed the crowd in a shoulder revealing turtle-neck sweater as she signed autographs at Mohegan Sun in Uncasville, CT.

Reese Witherspoon was spotted running in Brentwood, CA this week. The “Wter For Elephants” babe’s first outside jog since getting struck by a car back at the beginning of September! Glad she is back on the move!

Kristin Cavallari was spotted at the Chinese Laundry Party in Hollywood! KC looked beautiful in a leggy white dress as she smiled for the paparazzi at the Redbury Hotel.

It seems that Jennifer Aniston‘s much-copied 90s haircut is still a favorite today!

Users voted Jennifer Aniston #1 in a new Bing survey released in conjunction with the launch of their new search feature that integrates your trusted Facebook friends into the convenience of your search. Aniston was the top choice for Bing fans when asked, “What celebrity would you trust to help decide what your new haircut should be, if they were your friend on Facebook”, beating out famous hair worthy celebs like Kate Gosslen, Donald Trump and Snooki.

What shocked MJ is that although fans may love Justin Bieber’s music, it seems they don’t share the same “Bieber Fever” for his locks, as the tween sensation was the least trusted celebrity to help decide a new haircut.

Reese Witherspoon’s classic understated style is a favorite among users as she beat out Sarah Jessica Parker, Blake Lively, and Lady Gaga as the top celebrity users would trust to help choose a piece for their summer wardrobe.

(This one we were a little shocked about!)

And when it comes to making plans for their upcoming Memorial Day BBQ? Users trusted celebrity chef Rachael Ray’s recipes over her Food Network peers Bobby Flay and Guy Fieri, when deciding what to cook for the BBQ.