How does the music-identifying app Shazam work its magic?

  Other than playing video games, it's the most useful thing you can do on your phone.

Playing games is useful? I really hope that was ironic.

While I do like having Shazam on my phone, I still find, y'know, making and receiving phonecalls, the most useful feature.

Unrelated note: Some blogger reverse engineered the algo and posted sample code on his blog as an education experience. He got a takedown notice and was forced to remove the post from his blog.

Can't find the source right now, will look it up if anyone needs it.