Tecmo's Undead Knights had a demo up on PSN, and gamers who decided to give it a try, noticed that it was not just demo, but the full game.
Speaking with D'toid, who noticed the free game, Tecmo told the site previously that he final code for the game had yet to be approved - yet somehow it still made it's way onto PSN.
When informing Tecmo of the mess-up, D'toid learned that the mix-up was thanks to the PSPgo launch and PSN additions.
SCEA has pulled it from the service, but not before quite a few people got a free PSP game.
More through the link.