Okay, here's who I have ID'd (left to right starting at Ewan, seated)... Ewan McGregor, Hayden, George, Natalie, Yoda, Darth, R2, 3PO, Samuel, Jar Jar, Jimmy Smits, Christopher Lee, Liam, dunno (woman seated), dunno (guy in white T-shirt.. Jake Lloyd, maybe?), Ian McDiarmid, Grievous, Billy Dee Williams (where's the Colt .45?), Carrie, Harrison, Chewie, and Mark.
Is the seated woman in the middle the one that plays Shmi Skywalker?