Well being an opensource game i think we should rather try to get mumble ( http://sourceforge.net/projects/mumble ) more popular and used together with Nexuiz! I know the alienarena guys also use it on a regular basis and as far as i know its just as good as teamspeak.
Mumble technically allows for us to distribute it together with Nexuiz or if its possible to also link against it for a real close integration (not sure if thats possible at all or if mumble is standalone). We could include a howto setup mumble in our server setup guide(s) to help admins set them up and to have them include a line in the sv_motd about mumble.
What do you think about that?