SInce 0.54, there is a command to get a general "teamstatus". This lists the number of support structures, the health & state of the main structure, and the number of builders.
I've also heard from old trem players that there was indications about team mates, like the kind of info one can currently find in the scoreboard.
Scoreboard and binding teamstatus to a key are all well and nice, but I think I would rather have those informations in the HUD. If (one of) those was present in tremulous, I would like to see some screenshots of it, as I'm tempted to give a try at having that in a mod myself.
One thing I'm wondering about is, how would a list of team mates be handled, when it becomes long?