UPnP media server for Linux?

Hi,

I'm running a Linux (Debian Woody) Xbox to serve MP3 files to
computers around the house. Mostly I do that using Samba shares. But
now I have a Netgear MP101 digital media player (a standalone hi-fi
component which uses WiFi to receives audio streams) which needs a
UPnP-compliant media server. I've found a few such servers for
Windows, such as the Twonkyvision server, but I can't find one for
Linux. Does anyone know whether one exists?

thanks

john