...its pretty damn cool. You can upload your whole collection to the cloud for free.
Listen anywhere, even offline. You can get to your personal music collection at home or on the go. Listen from the web or your Android 2.2+ phone or tablet with the Music app from Android Market. Not online? No problem. With the Music app, you can select the specific albums, artists and playlists you want to have available when you're not connected. And the songs you've recently played will automatically be available offline.
They just announced it