Artists have come to realize that podcasting sells records. That's the reason behind the success of places like the Podsafe Music Network. Record Labels, on the other hand, are so wrapped up in their suits and cigars that they refuse to believe that podcasting sells records. Hence the reason why you won't find very much "signed" podsafe music. It mocks the outmoded business model which annoys the lords.
Magantune differs from other podsafe music sites because Magnatune isn't a directory where bands can create an account and upload their music. Magnatune is a real live record label - but a record label that understands podcasts sells records. The advantage of Magnatune music vice other podsafe music sites is the same as the advantage of a podcast network vice a directory. Since Magnatune is an actual label, John and the crew only sign artists that they feel are marketable (meaning GOOD!). Yes, it's subjective, but the quality level of a Magnatune album is consistently good whereas it can be all over the board in an unpoliced directory.
Anyone is welcome to play Magnatune music streamed right off the site as long as the 'from Magnatune' trailer is left in it. However, most podcasters are going to need the audio file to incorporate into the show. In order to get your hands on the actual albums in a staggering variety of formats, you'll have to contact Teresa and ask for a special "credit card" number to "pay" for the music you want to play.
We've actually played so much Magnatune music that we've had to start using music from the Podsafe Music Network simply because we've pretty much played everything we like from Magnatune.