According to Eurogamer the Vita can play PS3 games via remote play. The game will be downscaled to PSP resolution to play, but future versions of the feature will allow developers to create a 480p specific version. The PSP resolution is 480x272, and the Vita has a 960x544 resolution.

http://www.eurogamer.net/articles/2011-11-24-ps3-firmware-to-enable-vita-remote-play-for-all-games