So far that it's scheduled to come out Christmas Day of 2008, and that Leonard Nimoy WILL DEFINITELY reprise his role as Spock in the movie. Also there's talk about changing the script so that William Shatner can also reprise his role as Captain Kirk, though it's not official yet if Shatner will do it.
That they do. Here's some more:
The voices of Picard, Riker, and Worf are indeed the real actor's voices! (Patrick Stewart, Jonathan Frakes, and Michael Dorn)
Picard and Troi (real voices of Patrick Stewart and Marina Sirtis)
Odo & Stewie as Quark (it is indeed Rene Auberjonois as Odo)
Brian & Stewie, in a spoof scene from ST II: Wrath of Khan