Justin Bartha, Ashley Olsen's new squeeze, is allegedly "a little bit psycho-y," and didn't handle being dumped by ex-girlfriend Lydia Hearst so well. We don't believe a word of it because we think he's dreamy. Lydia's pals Blake Lively and Leighton Meester attended Nylon's Young Hollywood party with respective boyfriends (and Gossip Girl co-stars) Penn Badgley and Sebastian Stan (Carter Baizen), but Meester and Stan PDA-ed a lot more. Meanwhile Chace Crawford and Chuck star Zach Levy have both tried and failed to pick up newly single Jamie-Lynn Sigler. John Stamos showed up at Morimoto on Thursday acting weird and with a nasty black eye, though a rep for the actor says he got it from a kickboxing accident. Ethan Hawke laughed when he saw a DVD of Gattaca for $3 at a Chelsea stoop sale. Real-estate mogul Aby Rosen celebrated his birthday with Samantha Ronson, the Trumps, Donny Deutsch, and Ian Schrager in the $70 million Forstmann mansion on East 71st Street.

Petra Nemcova kind of stalked Sean Penn at a variety of different Cannes parties, even though he's back with ex-wife Robin. Mischa Barton was spotted knocking back tequila shots and smoking a joint at the Hotel du Cap in Cannes. The Bushes are blaming the wedding singer for leaking details of Jenna's nuptials. A vodka-swigging Brody Jenner went to six bars in less than two hours in Chicago in search of female companionship. Pete Wentz and Ashlee Simpson had an Alice in Wonderland–themed reception after their wedding on Saturday. (Maid of honor Jessica brought Tony Romo as her date.) Mike Tyson, now a sober Muslim, demanded that caterers get rid of pizza with pork and take down Grey Goose advertising in the VIP section at the after-party for James Toback's documentary about him. Kathy Griffin says Apple billionaire Steve Wozniak had his secretary dump her over the phone, and that he married someone else three weeks later. A celebrity assistant named Dan McMann planted an item in "Page Six" about himself. "Page Six" wonders if favorite whipping boy Keith Olbermann is on the verge of having a "professional meltdown" at MSNBC, but their evidence is minimal at best. Cindy Adams says Barbra Streisand switched agents because she wants to start acting again.