Well, they're not [link|http://bbcworld.com/content/clickonline_archive_31_2002.asp?pageid=666&co_pageid=4|calling it that].
Shazam's technology works by matching the mathematical make-up of a song with one million songs contained in a central database. When it identifies the song that's playing it sends you a text message to tell you who it's by.
When I heard this on the radio, there was some question as to whether the business model could sustain the infrastructure investment. No one mantioned the fact that this will make a perfect test of real-time watermarking/DRM enforcement.