8Tracks is a wiser and better timed muxtape in that they seem to follow DMCA guidelines (like you can't skip more than 3 tracks an hour.) Also, they obviously have a deal with Amazon, as there's an auto-link to the Amazon Mp3 store for each track. They also must have secured rights to the catalog. I don't know if 8tracks.com is a spinoff of a bigger company that has acquired rights to stream music, but I wouldn't be surprised.
The music industry may still be stubborn, but they have gave in quite a bit to the digitial world far more than they did only a few years ago. Look at the trend of music purchases, and even the music industry had to face reality at some point.
I stress this is my take on it. I don't know any inside info on 8tracks at all, and I only know a few of the DMCA rules for streaming.
