I don't know about other areas but every Wal-Mart I've seen (Savannah Ga, Augusta Ga, and all points in between), it's like this: Huge Wii Section. Huge DS Section. Huge PS3 Section. Huge 360 section. 5-10 PSP games buried in the PS3 section.
Every Gamestop/EBGames I've gone to has been like this: Huge PS3 wall. Huge Wii wall. Huge 360 wall. Huge DS wall. PSP games hidden on a little shelf that I can't even find without asking a sales clerk. It's usually hidden behind the PC games. All of the games look used, too. The Gamecube/PS2 sections are better organized. It's like the PSP is a dead system or something!