[Laurent]

Sean Penn Steps Out with Petra Nemcova at Oscar Parties
The actor is spotted with the model, who tells PEOPLE, "We are friends"

Less than two months after he announced his separation from his wife of 11 years, Sean Penn hit Sunday night's Oscar party circuit with a new blonde beauty on his arm: model Petra Nemcova.

The two arrived together (or, at least, simultaneously) at the Elton John AIDS Foundation screening party. Although they separated briefly – he did an interview while she posed for pictures – they eventually reunited for the cameras, as Penn wrapped his arm around her for a few photos.

So, are they dating? The actor, 47, and model, 28, avoided any clear-cut PDA. And when asked about her escort, Nemcova, wearing a custom-designed Roberto Cavalli dress, would only tell PEOPLE, "Yes, we are friends. He is on the advisory board of my charity."

Friends who've been spending quite a bit of time together: A source confirms that the two also hit L.A. hotspot Villa the night before.

Penn announced his separation from actress Robin Wright Penn just after Christmas. In the divorce papers, both cite "irreconcilable differences" and ask for joint legal and physical custody of their two teenagers, Hopper Jack, 14, and Dylan Frances, 16.

Last year, Nemcova made the Oscar party rounds with then-boyfriend James Blunt. But she and the "You're Beautiful" singer split shortly afterward.

Sean Penn Steps Out with Petra Nemcova at Oscar Parties - Oscars 2008, Petra Nemcova, Sean Penn, Red Carpet : People.com