iPhone/iPod touch only: Free music discovery service Last.fm has launched its own iPhone/iPod touch 2.0 app, and it does exactly what you'd hope it would, with a few caveats. The interface is straightforward and simple, at least for experienced Last.fm users—launch the app, then choose from your "Recommended Radio" or enter an artist name to hear other tracks you might like. You can ban, skip, or "Love" tracks while they're playing, and get artist bios and other information. The big downside (inherent to the iPhone) is the lack of backgroung playing, so you've got to keep the Last.fm app up while you're streaming your music. At the same time, the app makes Safari recognize direct lastfm:// links for convenient linking and playing. Hit the jump for a video demonstration and a direct link to the free app in the iTunes Store; jailbreak fans, check out MobileScrobbler for a similar solution.