NotaLobby 2.1 for Linux is released, check it out here:
http://springrts.com/phpbb/viewtopic.php?f=64&t=27289The devs have really done a great job on it. It is lacking some features, but overall the interface is extremely stable and slick. And it has all the most important stuff: joining multiplayer battles, chat, map downloader, and even integrated rapid downloader. Also, I have not tested, but it should have the parts required for potential matchmaking to work.
Try it out, and if you like it make sure you let the devs know they are doing a great job. :D
Edit: (Obligatory screenshot)