Gavin was there to perform at Condé Nast Traveler's Hot List Party, where his good-lookin' wife, rockin' a sheer black top and high-wasted shorts, came to support her main man.
Jeez, could this be one of Hollywood's more functional couples?
"Gwen and Gavin were side by side at a table in the VIP area inside when they first got there, laughing with a few friends," dishes a fellow clubgoer. "It looked like they were having a lot of fun together."
When it was time for Rossdale to perform his acoustic set, his wife was nowhere to be found! So did she take a cue from the rest of her famous pals and watch her hubby from a superprivate room? As if.
"Once Gavin left to go to the stage, Gwen walked out shortly after him," says our spy. "I thought she left, but then once Rossdale came on in the middle of the club, you could see this bright blonde in the very front row dancing and swaying her arms. It was Gwen."
Too adorable! We love that Stefani is Gav's No. 1 fan. Don't know many famous wives who would get down, literally, in the middle of all the common folk. Fab.
Meanwhile, Kate Beckinsale held court with some pals at G & G's VIP table.
Howevs, just the night before, the younger Hilton sis stepped out on the town with her man of four years—trying to show that her relationship isn't quite as tumultuous as her sister's.
Trust fund babies Nicky Hilton and David Katzenberg enjoyed an Italian meal with friends at Giorgio Baldis in Santa Monica Friday Night.
While their relationship is so on, it must have been an off-day for Nick, 'cause our source said the usually more stylish sis didn't look the best, seeing as she was "carrying a hideous bag."
Although we have to admit, anything Hilton's carrying nowadays is a step up from those Samantha Thavasa bags she used to design.
Across the globe and far less flashbulb hot was...
Stevie Wonder, who was spotted out 'n' about in the capital city of Accra, Ghana, where he was in town to pay respects at the funeral of an old friend.
The singer has spent time in Ghana over the years, where he has written music and supported activist causes.
—Additional reporting by Kate Alper
See who else was partying it up in Sin City this weekend in our Party Pics: Vegas gallery.