We'll tests are starting to show that Comcast is indeed messing with BitTorrent traffic. Since there are at least some legitimate uses of BitTorrent it will be interesting to see how this progresses. I doubt your day to day MP3 pirate will bring a lawsuit against them, but perhaps some company who's business is hurt by this will.
I have also heard rumors of Comcast terminating VPN connections regularly. When contacted they claim that using your connection for business use (work) is against the service agreement.