According to the company, the web-based solution enables users to listen to songs from their music collection, as long as it’s not DRM protected (bought from Apple's iTunes store), on their smartphone if they are within range of wireless service. And, keep in mind, as with any content service, data charges from your carrier apply.

The player recognizes iTunes playlists, artist names, album names, song names and musical genres. In the beta users can share up to 250 songs with friends and remotely listen to music even when their PC is turned off. It supports the MP3, AAC and WMA audio-file formats.

You can sign up to take part in Avvenu's closed beta here. The company is limiting the number of participants, so if you want to try it out sign up quickly.

Once you provide your mobile phone number, you'll receive an SMS message on your smartphone with instructions on how to get up and going. You must already have an Avvenu account and, of course, an iTunes account (Windows XP only) and a Windows Mobile device.

Avvenu smartly recommends users of the service have an unlimited data plan. It also says users must store the music they want to hear on their Windows Mobile device as Anytime Playlists in the Anytime Music section of the web-based Avvenue Music Player: Once selected, these playlists will stream up to the company's servers so they're available when you want to hear them on your smartphone.