The closest thing to an mmorpg on a psp was my friend who did some ---- to his psp and hook it up to his computer and played runescape on it. Thats it though.
the one driving game i played had extremely long load times, they're fun, if you like to wait but ya, no mmorpg's its slow as hell even with a shared UMD multiplayer game, I couldn't even imagine an mmorpg.