In Christmas of 2008 with producation to start in Fall of 07. It is official check out TrekMovie.com. There's an actual press release on that post and we know that JJ Abrams who was involved with last summer's M:I:3 and ABC's Lost will be producing and directing the film. In addition to that though take the rumors of plot and characters with a grain of salt.
Officially we don't know who they are yet. Rumors are that we will see the troika of Captain James T. Kirk, Mr. Spock, and Dr. Leonard McCoy to be played respectively by Matt Damon, Adrian Brody, and Gary Sinise (yeah Lt. Dan is a dead ringer for DeForrest Kelly LOL). Let it be known though that the new Star Trek movie will respect Star Trek canon so the new creative team won't just throw in too much new stuff into the mix.
EDIT: In the comments of the casting rumors, Beyonce as Uhura, that made me a smile. I'd be intrigued by that.