Hi!
I figured it was time to decloak and look at the forums since my copy of Tacops4 has just been ordered.
I run a battlefield 1942 clan (2nd world war combined arms shooter), which regularly has 12-16 players per team, and after MUCH argument we've found teamspeak (http://www.teamspeak.org) to be the superior voice comms solution for audio quality, price (free), and features.
It allows keyboard shortcuts to hop between different channels, and creating your own (passworded) channels on the fly, as well as 'whispering' to people or channels. It supports a Unix based server for client-server comms (which scales _far_ better than the peer-to-peer comms of rogerwilco), and works acceptably on a 56K modem (although most of the clan have DSL).
Voice discipline is a pretty important part of it, and I agree that we need text based comms as well, but for discussion rather than detailed orders (and for a healthy bit of banter!), we find voice comms to be an invaluable bonus, particularly as you don't need to take your focus off the game (which of course is more of an issue in an FPS).
If I get time to attend a future CPX (and my copy of tacops 4 shows up , I'll host the Unix server on my colocated box (in Germany, but reasonable connection to the US), and that can be included in people's testing of solutions.
cheers,
bvark / phil sykes (3rd rate tacops v1 player, 1996/7