Yeah, i know, I'm late.
The ".mp3" extension turned 10 on July 14th.

An interesting bit of information: Back then a major point of critique was that the MP3 encoding technology was thought to be too complex.
I guess that teaches us not to underestimate the speed at which technology evolves...

Read all about it:
http://www.iis.fraunhofer.de/pub_rel/presse/2005/mp3/index.html