i dont think is about giving away free stuff but the fact that you can pick your price. This seams like a very interesting idea. First of all, 10bucks are worth a different value depending where you live (state, city, social background aso) and music might be worth as well some different level for different people.
some are willing to pay more, some cant, some wont aso.

i dont know if it works, but as you can see when looking at tools like gamestudio, different people have different needs. and adapting your offer to their needs and possibilities doesnt sound dumb to me.

plus it can lead to more hardcore radiohead fans.
i know that the first title i heared wasnt one i bought but one i stumbled over. having the opportunity to get more legal music might end up in having more sales in the end.

freeware music had that effect for a lot of stars and the internet is an indies dream come true. this might be another logical step.

but basicly i think radiohead has unterstod that a fan base is the key effect for success. not sales, not pr and nothing else. having fans, getting new ones and keeping them satisfied is what makes the difference and works on a long run.
no pr machine or money can compete against that if you look at a range of 10-20 years.

cheers