Today Thierry has just pushed out the full Taste Profile addition to the Million Song Dataset. This includes user-play data for over a million users. Specifically the data includes nearly 50 million play count triples (user-song-playcount) for a million users and 385 thousand songs in the Million Song Dataset.
The data is provided by The Echo Nest (awesome company, that Echo Nest). Thierry also hints that there may be a contest similar to the Netflix prize coming soon. Should be a fun way to spend the holidays. Read more about the data here: The Echo Nest Taste Profile Subset.