Mike Tran/Getty Images

At the brand new Hyde nightclub in Vegas' Bellagio hotel, special guest for the evening, Sophia Vergara, best known for her role as Gloria on TV sitcom Modern Family, arrived at the lounge looking stunning in a white, shimmering dress. When asked about her New Year’s Eve at Hyde, Sophia replied, “I’m very excited … I was a fan of Hyde in Los Angeles, so I’m sure [Hyde] in Vegas is going to be even more fabulous.”

Welcoming the New Year at Hyde Bellagio were Wilmer Valderrama, Joe Jonas, Leona Lewis, Eliza Dushku, Emile Hirsch, Lauren Conrad, Stephanie Pratt, Eric Stonestreet, Amber Lancaster and Lakers basketball player Rick Fox, among others.

Guests settled into their plush VIP tables as models in cellophane dresses posed around them holding celebratory New Year’s balloons. Songs like Tyga’s “Rack City” and Drake’s “Take Care,” featuring Rihanna, had clubgoers on their feet dancing and raising their glasses to a successful 2011.

Vergara pumped up the crowd as she counted down the remaining seconds of 2011. As the clock struck midnight, the iconic Fountains of Bellagio sprayed high above the Las Vegas Strip and gold and silver balloons filled with $100 bills fell from the ceiling. Throughout the venue, guests cheered, toasted and kissed to the year ahead.

It's a scary time of year to be in Hollywood!

Tons of celebs stepped out for Universal Studios Hollywood's Halloween Horror Nights over the weekend. Demi Lovato brought a bunch of pals with her, including BFF Hanna Beth, as did Dancing with the Star castmates David Arquette, Ricki Lake, Kym Johnson, Chaz Bono and Cheryl Burke.

Demi had such a great time at the amusement park that she even Tweeted about it, writing, "Just thinking about how excited I am for Halloween! Went to @HorrorNights @UniStudios this weekend and it was sooooo scary - loved it!!"

Wilmer Valderama, Elijah Wood and former One Tree Hill star Chad Michael Murray also hung out with some ghastly creatures.

But David with his old co-star, Scream's Ghostface Killer? Hands down the funniest duo of the day. Sorry, Ricki!

The event runs at Universal Studios through October 31.

Last night Wilmer Valderrama was spotted heading home after attending ex-girlfriend Demi Lovato's show at Club Nokia in downtown Los Angeles, and he tweeted, "Just left @ddlovato's LA concert.. No words to describe how proud I am of you.. Let your passion & self commitment inspire the world." Aww, how sweet! I mean, who knew the dude who played Fez on That 70s Show would be so moved by Disney-manufactured teenybopper rock?

Who else did we spot out and about last night? Josh Duhamel was seen grabbing some food at Tavern in Brentwood, and Josh Henderson hit up Tru nightclub in Hollywood. Check out the pics of the boys in the gallery below!

After a bitter breakup with Joe Jonas (and before she entered a treatment facility for "emotional and physical" issues), Demi Lovato hooked up with Wilmer Valderrama, according to the NY Post.

18-year-old Demi and 30-year-old Wilmer first connected when they filmed a PSA in Chile for earthquake relief in March, and a few months later Demi was introducing Wilmer as her boyfriend. "The two started seeing each other in May right after her breakup with Jonas," a source on the tour said. "She would show us pictures of them together."

Lovato's rep had no comment while Valderrama's rep denied a relationship. Wilmer has dated everyone from Mandy Moore to Lindsay Lohan to Ashlee Simpson over the years, and even though he's not getting any younger, he doesn't exactly seem like he's willing to settle down anytime soon. Is it possible that the heartbreak of not one but two failed relationships was what sent Demi over the edge?

Wilmer Valderrama celebrated the beginning of the end of his 20s in Vegas (natch) with celeb friends including Nicky Hilton and David Katzenberg, who will apparently go anywhere they're invited!

Man, Wilmer's really starting to show his age. Guess that's what dating Lindsay Lohan will do to you!

Say WHAT?

The luminous star of Mean Girls, The Notebook and Red Eye put on her Sunday best (er, well, she could've worn something a bit more flattering, but I'm just happy to finally see her!) to celebrate her 30th birthday at Beso last night... but she wasn't celebrating with Ryan Gosling!

An X17 inside source inside the Hollywood hot spot tells us that Rachel and Wilmer Valderrama "were sitting at the same table and hanging upstairs at Kiss Lounge." Any hanky panky goin' on? Nope - our source says they were "just hanging out platonically."

Our source goes on to say that "Rachel may want her ex Ryan to think something different, of course, as he was not in on the festivities... and DJing at Bardot instead. Clearly that relationship is O-V-E-R!"

If Ryan is still dating Rachel, he should be with her on her birthday!

This weekend was a big one for house parties, launch parties and premieres, but celebs still managed to find time for charity! Jada Pinkett Smith, Jamie Lee Curtis, Jason Priestley, Wilmer Valderrama and Melina Kanakaredes were just a few of the stars attending the 15th Annual Dream Halloween by the Children Affected by AIDS Foundation in Santa Monica this weekend.

Our cameras also caught a bunch of cute kids, but when they're in costume, it's hard to tell who they are: child stars or celebrity spawn? (Check 'em out in the gallery below!)

We caught Wilmer kissing a mystery girl on the set of his new TV show "The Emancipation of Ernesto." By the looks of his powder blue members only style jacket ... we're guessing this show is going to be set in the early '80s?