Celebs celebrating the New Year!!

BLACK & GOLD

Also making it a couples night in Las Vegas: deejay Joel Madden and Nicole Richie, who co-hosted a party at LAVO.

POP STAR

At her New Year's Eve concert in New York's Madison Square Garden, Mariah Carey toasted 2010 with a glass of Champagne and a very special guest: husband Nick Cannon, who manned the deejay platform and ended the set by kissing his wife (not pictured).

LADIES NIGHT

Back in Hollywood, Lauren Conrad and her girls – Stephanie Pratt (left) and Lo Bosworth – partied at Beso, but at least one of them was feeling the effects New Year's Day: "My legs are so sore from dancing!" Pratt Tweeted.

NY STATE OF LOVE

Even among the million-plus revelers crowded into New York City's Times Square, Jennifer Lopez and Marc Anthony found a little space for romance under the bright lights.

STEPPING UP

From "Let's Get Loud" to just kickin' it: J.Lo and Marc Anthony join host Ryan Seacrest on Dick Clark's New Year's Rockin' Eve to form their own Rockettes line in Times Square.

NEW SIGHTS

Goodnight, 2009 ... Good morning, 2010! 90210 star AnnaLynne McCord sees in a new set of numbers while hosting a party at W South Beach. And who'd she kiss? She told guests her peck would be reserved for sister Angel. Aww ...

WHEN IN VEGAS ...

From the turntables to the mic, Pete Wentz celebrated rock-star style (tattoos and all!) at JET nightclub at The Mirage – but it seems he had something else on his mind, Tweeting: "Missing @ashsimpsonwentz in town."