In the most recent issue of the Japanese magazine Famitsu, two sequel announcements were made for the PSP. The first is a new Ridge Racers title from NAMCO. In addition to new tracks, this version will feature remakes from Rage Racer, Ridge Racer Revolution, and Ridge Racer Type 4.
The other is a follow-up to Taito's great action/puzzle game Exit. Titled Kangaeru Exit in Japan, it'll have 110 all new levels and reportedly will downplay the action elements. Kangaeru Exit is slated for release as soon as September, though nothing has been mentioned for the US.