Linux Games has received word from Timothy Besset, the project lead on QERadiant/GtkRadiant who is also in charge of the Linux port of Quake III Arena and, apparently, Return to Castle Wolfenstein, that a dedicated Linux server for today's multiplayer test demo will be released, but not a Linux client. Here is the update:

There will be a linux dedicated, no client yet... maybe a few days after the test is out... there will be a linux dedicated .. we've been testing it for a while .. as for the client I haven't started with it yet