As has now been reported in several places, Comcast is limiting BitTorrent traffic. The easiest way to fix this, and get back at Comcast, is to switch to a different ISP. But if you are stuck using Comcast, you can still configure your BitTorrent client so that it can be used on the Comcast system.

The key is to use encryption. If your traffic is encrytped, Comcast can't identify it is as BitTorrent traffic and they will let it through. How you enable to encryption varies based on the client you are using so poke around in your preferences to find the correct panel where encryption can be configured. When you are configuring the encryption, make sure that you don't just enable it, you want to make sure that encryption is forced. If you don't force encryption, you'll still connect to peers that are not encrypted and this traffic will get blocked by Comcast.