The Ratchet & Clank and Resistance franchises will still be worked on exclusively for the PS3, as those IP are owned by Sony. But Insomniac Games' new IP will appear on both the PlayStation 3 and the Xbox 360.
An eye for an eye, an Insomniac for a Bungie, as they usually say. Or do they? *snicker*
For more information, do click on: http://kotaku.com/5547071/ratchet--clank-makers-next-game-coming-to-the-xbox-360-ps3