I emailed codemasters (as I noticed someone else did in this thread or another on the forums).
I specifically asked about hosting multiplayer games for the PC on a dedicated server or whether it would be peer to peer. this is their answer:
Thank you for submitting your recent request to Codemasters Customer Services concerning Operation Flashpoint: Dragon Rising.
Operation Flashpoint: Dragon Rising does not support dedicated servers unfortunately. The game, at launch will be peer to peer only.
so this means I can take down the threads on our clan website saying we would start OFP as part of our clan and saves me buying the game as I'm only interested in multiplayer - a shame because quite a few people are buying the game.