The rumors were correct, LittleBigPlanetis heading to PSP and it'll be here before the end of the year. Announced at today's Destination PlayStation retailer event, the PSP version will be developed "in conjunction" with Media Molecule and will offer a similar experience to the PS3 version with players being able to play, create and share on the go. We're promised plenty of new content, such as levels, exclusive to the PSP version this fall.
We'll be very surprised if we don't see any cross-platform interactivity, but details are very thin on the ground. We'll keep you updated as more information is revealed.