Little is known regarding each game. Joystiq reports that Rock Band Unplugged will sport an in-game music store through the system's wireless capabilities, and adds that LittleBigPlanet PSP is being made "in conjunction" with creator Media Molecule.

Rock Band Unplugged will be "launching exclusively on PSP," according to Sony PR. Assassin's Creed will be "an exclusive installment," and LittleBigPlanet will pack new levels and areas "specifically created for the platform."

As for MotorStorm, the portable rendition of Evolution's racing series is said to feature the "breathtaking yet lethal and unpredictable setting of Alaska." It's dubbed MotorStorm Arctic Edge, developed by Pursuit Force veterans Bigbig, and will also hit PlayStation 2.

LittleBigPlanet, Rock Band Unplugged, MotorStorm and Assassin's Creed PSP are due out later this year. Expect more details once the non-Sony games, Rock Band and Assassin's Creed, are officially announced by their respective publishers.