Upcoming PSP RPGs off the top off my head:
Ape Escape RPG
Tales of the World 2
FFXIII Agito
Kingdom Hearts
Brandish
Disgaea 2 Portable
Persona
Parasite Eve
Cardboard Senki (Level 5)
Ushiro (Level 5)
Harvest Moon: Sugar Village
Zill O'll Infinte (Koei)
Mana-Khemia Portable
Narisokonai Eiyuutan (Irem)
Class of Heroes (Atlus)
.hack/link
All GBA ports, apparently.