Spin.com has a great article up concerning music leaks. It really is the first article I've seen that makes mention of zip file sites like You Send It, Megaupload, and Rapidshare, which I think are much more involved in leaks than anyone in the media realizes. Just go check out Radiohead fansite Ateaseweb if you don't believe me. Sure, more people probably use P2P sites, but I have a feeling that if you don't use OiNK, you're on something like Albumbase, which I really like. Once again, great writeup.
