One game that managed to slip under our radar, most likely thanks to the 200 Million Dollar juggernaut Halo Reach blocking its path, is Phantasy Star Portable 2.  Both games were actually released on the same day.  The sequel to the first Phantasy Star Portable title, PSP2 fixes one huge problem we had with the original PlayStation Portable title - online play.  The original title only feature local wireless play while the sequel supports full four player co-op via the internet.