Some great news from a quality free PSP site and a great addition to the PSP Community: PSP Vault
"Exit" came out in Japan today. There are screenshots all over the place, but I suppose you've already seen them at your site of choice. The art style of this game is supposedly second to none, so I'll have to give it a shot when I get a chance.
It looks like downloadable content will also be released for this game; the official webpage says that 10 stages will be playable per pack, and they'll release several packs throughout the game's lifetime. Right now it looks like they have 4 packs scheduled, and 1 is already available: http://www.exitgame.net/pc/h_download.html