The link on the top of the page that says "Get Android App" sends you to the Google Music Beta app which offers a limited free trial, but does not allow you to purchase tunes from the Android Market. Longer than expected negotiations with the record labels is holding this feature back. The app allows you to store up to 20,000 songs for free and lets you access them from any Android device running Froyo or higher. You will also be able to create your own playlist and listen to your songs even when offline.
Right now, it is available only in the U.S. and it requires Flash to be installed. If you want to start your music collection now, some free tunes are available from the service. Add all of this functionality to a brand new Google Music Store, and it looks like iTunes will have some tough competition.
source: NewsonDroid via TechCrunch