For an in-game lobby, that's something that requires central servers, which I just don't have the money for at this stage. The other reason is that I just don't think that pvp-style matching as you see in other games would be really appropriate here, since the games are so long and require so much cooperation (and coordination of schedules). However, there has been talk of potentially adding XFire or Gamespy support, but that's just been lower on my list at the moment compared to gameplay issues, etc.
Thanks for your support!