According to the latest Cheat Code Central Podcast, they mention that Rockstar has gone Sony Exclusive, and that their upcoming titles other than the ones already in production, will be some sort of a PS3 exclusive.
They start talking about it at around around 50:00 minute into the
Titles known to be in development for the PS3 include
-New Rockstar PS3 franchise
-Red Dead Revolver 2?