SCEA's Bend Studio has just announced (via the Playstation Blog) that Resistance 2 coming to PS3 this year, and Resistance Retiribution, coming to PSP this year, will be able to connect via a USB cable to add features to R2.
While playing in “infected” mode, Grayson wears a Specter uniform and has glowing Chimeran eyes. He gets to use one of the new weapons from R2: the HE .44 Magnum, which fires explosive rounds that can be triggered remotely. He has regenerative health and no longer needs to look for health packs. He can breathe underwater, allowing him to reach hidden areas that he could not reach before. And we’ve added another whole class of Intel that are hidden throughout the levels. Collecting all of the “infected” intel will unlock another R2 weapon, the Plasma Grenades."
Also announced is PSP Plus which will allow you to play Resistance Retribution on your PSP using a Dualshock 3 controller.