PSP Plus Brings DualShock Control to the PSP
Sony is adding rumble support to the PSP, courtesy of the DualShock 3. Using the new "PSP Plus" feature in games like Resistance: Retribution, owners of both the PSP and PlayStation 3 will be able to forego the portable platform's analog nub for a better control experience.
By plugging in your AV-output capable PSP (2000 or 3000), you'll be able to switch on PSP Plus through Resistance 2. Doing so adds DualShock 3 support, disables aim assist in Resistance: Retribution and lets the player alter their control layout to take advantage of the PS3 controller's extra inputs.
The option requires that gamers have a copy of Resistance 2 in their PS3s, but will not require a firmware update for either the PSP or PS3
Resistance 2 Discussion Here
Resistance: Retribution Discussion Here