So far, it's been a pretty good summer for just about any type of RPG fan who owns a DS. Nearly every RPG type has been represented by a game this summer:
Strategy RPG: Final Fantasy Tactics A2
Difficult first-person dungeon crawler: Etrian Odyssey 2
Remake of RPG classic: Final Fantasy IV
Rogue-like: Izuna 2
Dragon Quest game: Dragon Quest IV remake coming in September (The Dragon Quest V remake was also recently released in Japan)

All this is topped off with the announcement of the Chrono Trigger DS port coming at the end of the year.