An onlooker tells Us Weekly that Keibler, 31, and Clooney, 50, arrived together just before midnight at the Ritz-Carlton's Deq bar for a business meeting with film executives.
Clooney looked his usual dapper self in a black suit and white button-down, while Keibler "looked stunning" and "so refined" with her hair pulled back, the witness says. Surrounded by the Ritz-Carlton's security personnel, "Clooney didn't bring any of his own team -- just Stacy."
And before sitting down for the meeting, Clooney made sure to introduce his pretty blonde companion to the group. "Looks like it's official!" the observer adds.
After a half-hour meeting -- with wine and a meat-and-cheese plate -- the couple got up to leave "with her arm on his."
On the way out of the Ritz, they ran into his Up in the Air director Jason Reitman -- who Clooney greeted warmly with a "big handshake" and quick chat. "Stacy watched, smiling at him," the observer adds.
32-year-old Canalis, meanwhile, is licking her wounds -- and, as it happens, following in Keibler's footsteps as a contestant on DWTS.
"The end of a relationship is complicated," she admitted to Italian mag Chi. "I went to the United States, because at the moment I could no longer face the world. Watching my life being dissected was not easy for me."
She added wistfully: "I have always seen cold and controlled men as the right ones for me," she sniffed. "You have to accept that Prince Charming who is coming to save you is not going to happen -- it works against you."