Google is listening; but only if you want it to.

The search giant is now offering to track the music you listen to on your computer, then publish that information anonymously for anyone to view. The new Google Labs program is called Google Music Trends.

In order to participate in voluntary eavesdropping, you must have a Gmail account and download Google Talk, Google's 1-year-old instant-messaging program. Once logged on to Google Talk, add a check mark next to the Google Music Trends option in its Settings menu.

Each time a participant listens to a song on Apple Computer's iTunes, the song information is registered by Google Music Trends via Google Talk. The program also supports Nullsoft's Winamp, Microsoft's Windows Media Player and Yahoo's Music Jukebox, according to the Google Music Trends Web site.

Google refers to this tracking as casting a vote, but more specifically, Music Trends monitors and collects information on the music you listen to on your computer.

Full story: news.com Google Blog