Radiohead just announced that it's running a fan-created remix contest at radioheadremix.com, where you can listen to remixes of "Nude" from In Rainbows, vote on your fave, and post your own.
I actually have a column coming out in a couple days on the benefits of artists going open-source with their music and encouraging fans to get creatively involved with it through things like remixing, so I like that Radiohead's going there. I just think the way they're going about it is a little off.
To remix the song you have to buy its "stems," as they're referring to the component tracks--i.e., vocals, drums, strings, etc. They're available as DRM-free MP3s for purchase through iTunes for 99 cents apiece, and if you buy all five stems you get an access code for a GarageBand-compatible project file. (Strangely, buying all five together costs you a dollar more than buying each separately.)
I think that if musicians expect their audience to work for them for free--which, when you break it down, is what's happening here--they shouldn't charge for the privilege, especially if they're the ones who made such a big deal out of releasing the actual album in a way that encouraged free downloading and trading.
Of course Radiohead has the kind of fans who will buy anything the band tells them to, and considering the number of remixes that have already been uploaded to the site, plenty of people aren't bothered by the situation.