I suspect few of the folks who read this site are deeply interested, but I've posted an addendum to the Unofficial Fedora FAQ -- how to enable MP3 support in Fedora Core 2. (Fedora is an otherwise-outstanding Linux distribution that removes MP3 support in order to avoid patent royalties.) It'll be linked-to from the FAQ shortly.
Enabling MP3 support in Fedora Core 2 Linux
Written by Adrian Holovaty on May 29, 2004