Many gamers are using BitTorrent through Valve's Steam. By which I mean, that p2p file sharing is hardly nefarious. It's just a clever use of bandwidth.
I think I got a little ahead of myself here, sorry. Bram Cohen (who is known for inventing BitTorrent) has worked shortly with Valve on Steam. I can't find a source quoting Steam as using BitTorrent though, so let's assume that no.
If they are not using BitTorrent then Sync would provide a new, plausible way to stop ISPs from blocking that specific protocol.