Of course, perfect as the PSP's screen is for watching movies, Sony's UMD format never caught on (big surprise), so don't expect to find many options there.
There's not much left to say. If you're in the market for a killer portable game console, this is one of the best deals I've seen. But it's available today only, so don't wait if you plan to pull the trigger.
Update: Sold out! Sorry if you missed the deal. As I noted in the above paragraph, this was one day only.