The other footnote in the Last.fm announcement was that unsigned artists could also upload music for streaming and get a little bit revenue from anyone playing the song. I don’t know how much, but I suspect it will be tiny amounts.
It’s interesting. Pandora does not have the same deals in place, so it could only stream inside US, just now. And it tends to repeat itself. So if you like to possibly hear the same tracks and be frustrated now and then, use Pandora. If you want to hear any music, but one track only three times, use Last.fm.
Somehow I think consumers would prefer something between these two extremes.