Shazam Encore, which has been updated as a game in the past, has finally received Mango treatment and has brought along some goodies. As well as fast-app switching, you're now able to pin the tagging functionality to the home screen to allow quick access. While Shazam is useful, Bing also offers music identification from a recording snippet too (for free).
You can pick up Shazam Encore for $5.99 from the Marketplace. What do you use? Bing or Shazam?