[tweakmonkey]

Last.fm - the Social Music Revolution

The selection's pretty big but not complete. You can search and play full length songs from major labels. It's almost easier than pirating!

Edit - here's an example: four full length Incubus songs Incubus – Music at Last.fm.

BTW, this isn't super exciting or breakthrough news, but it's a step in the right direction.

Edit2 - Ars wrote about its limitations here: Why Last.fm's free music won't replace your music collection