Not a forum to "discuss" that I can see, just a calendar to place your trip for anyone who cares:
http://www.flyertalk.com/flightconnect/
(I'm just guessing at its function; I've never actually used it.)
If there were a place to discuss, it would presumably be in the Community group of forums. That's I think where group trips in the past have been discussed, but I'm not sure where exactly in the Community forums.