I'm pretty stoked about Amazon. As I said earlier in this thread, I've been using them the most lately (over buying CDs) and it seems to make wayyyyy more sense.
Why buy the whole CD when you can buy the two good songs on it for less than a couple bucks? And later on if someone requests a different song on the CD... buy that track too.
I hope other stores (and record companies) follow Amazon's example - and I hope that their example is good enough for others to follow. The time can't be far away when they realize that while CD's are just fine (and until now I've preferred them, whether I rip them to mp3 or not,) digital downloads are the future and the future is now.
I myself am not overly worried about the legality of using Amazon, iTunes, Walmart, etc as far as DJ'ing is concerned. Even if it made it to court (and I still think the warnings are regarding the ASCAP, etc fees anyway) I don't think it would make it very far. IMHO, if an individual has receipts, whether for CDs or digital downloads, for all his/her music, he needn't worry -- whether it's for personal use or public performance -- as long as the venue is taking care of the appropriate licensing fees.
Just my $0.02