Hmm... the previously mentioned TremZ project, which btw changed name to "Unvanquished" (which I find much less catchy than the previous name) has released as promised their first alpha on the last day of February.
However as I can't get it to run on Linux (nor on Windows for that matter), I will have to rely on forum postings from which I extract that it really is an alpha and you shouldn't get your hopes too high that it is much more than Tremulous at this point (graphics and game-play wise)...
|WIP Unvanquished playermodel|
Edit: A somewhat controversial split-up seems to have happened in the development team. Read here about one side of the argument... you can find the over side of the discussion also via the forums or the irc channels. Not sure what to make of it, but I will keep you informed as soon as the dust has settled ;)