'24': The Movie?
One of the ideas currently being tossed around would have half the film transpire like a normal movie with the real-time gimmick kicking in with an hour left in the movie. As for the plot, they're waiting to see exactly what transpires over the next two seasons before commiting to anything.
Perhaps if they know in advance they can have the end of one season lead into the film with a bitchin' cliffhanger. The last season ended with Jack Bauer (Kiefer Sutherland) presumed dead and left to wander the Earth on the lam from pretty much everyone (especially the Chinese government -- who want him in prison for the death of a consulate).
Source: Calgary Sun, by: Mike Sampson