Tom Cruise and Katie Holmes ran into Nicole Kidman, Keith Urban and Penélope Cruz, while newly split Cameron Diaz and her ex, Justin Timberlake, were at the same bash and then later at another party.
Diddy arrived outside a party just moments after his ex, Jennifer Lopez, arrived with her husband Marc Anthony.
Yes, our party spies were everywhere for Hollywood's all-night celebration.
Earlier in the evening, Diddy beamed about his ex, J Lo, to our special correspondent Carrie Ann Inaba.
"Jennifer and Marc, they never let you down," he said when asked who the best dressed lady of the evening was.
"Extra" has learned that after leaving the party, Marc and J Lo made a pit stop at McDonalds before hooking up with new BFFs, TomKat, Victoria "Posh Spice" Beckham, Leah Remini and her husband Angelo.
At the InStyle Warner Brothers party, Cameron Diaz partied with her "Gangs of New York" co-star Leonardo DiCaprio, while we spotted her ex, Justin Timberlake, hanging with Sheryl Crowe and Eva Longoria.
Felicity Huffman cut a rug with a friend and hubby William H. Macy as Heidi Klum and Seal got their groove on.
The "Lost" castaways struck a pose, and Courteney Cox Arquette shared a laugh with Kelsey Grammer.
Carrie Ann witnessed a moment you will only see on "Extra," as Sharon Stone, who is an "Ugly Betty" loyalist, congratulated America Ferrera on her win.
"Congratulations! I'm really happy for you, honey," Sharon told America.
At the Paramount Pictures bash, our Jerry Penacoli partied with the cast of "Dreamgirls," including "it" girl Jennifer Hudson.
"Extra" also spotted Jamie Foxx and Sharon Stone at the Weinstein Company soiree and Kiefer Sutherland at the FOX party.
These Hollywood superstars better rest up from their big night out; the Oscar parties are just around the corner!