In response to the post below:
A stumbling block? Have you given any thought to what this application does? Allow me to enlighten you:
In the beginning, there was Napster. Everyone downloaded music from everyone else, and it all worked through a central server. But the server was shut down, and napster was no more. Then came gnutella in it's various incarnations such as Limewire, Bearshare, etc. This was a decentralized version of napster, where everyone connected to a few other random users, and they were connected to a few other random users, and on down the line. This was very cool until the music industry started to corrupt the system. Now half the "people" you connect to are RIAA computers, dishing out fake results, and music files filled with static. In addition, they monitor traffic on these networks and attempt to sue hundreds of users a week!
Enter Maestro. It's a revolutionary, responsible and safe way to share music. It works just like people have been sharing music for decades: by sharing with your friends. Think about it. Do you share similar music tastes with your friends? Are you ever been introduced to new music from your friends? Do you ever tell your friends about a new band you like, or swap CD's with your buddies? This is a digital extension of the way music sharing has been working since before CD's. It's much more responsible than simply sharing your mp3's with the entire Internet. And it's safer! The RIAA won't be looking at your iTunes library, and when you download songs from others you're downloading songs from trusted sources.
You said there's no way to find other users. How do you find friends in iChat? And would you really want hundreds of unknown people trying to connect to your iTunes library anyways?
There's a lot more under the hood of this application as well. You can automatically connect to other users on your local network. And it uses jabber to provide decentralization. You can even subscribe to your friends' playlists, and have songs downloaded for you automatically!