Comcast actively blocks P2P traffic

Farhad Manjoo of Salon says,

The AP has a good scoop today. It found that Comcast directly intervenes in communication between two peers on a P2P network, closing down connections on BitTorrent, Gnutella and other systems.

Snip from that AP story:

Comcast's technology kicks in, though not consistently, when one BitTorrent user attempts to share a complete file with another user. Each PC gets a message invisible to the user that looks like it comes from the other computer, telling it to stop communicating. But neither message originated from the other computer – it comes from Comcast. If it were a telephone conversation, it would be like the operator breaking into the conversation, telling each talker in the voice of the other: "Sorry, I have to hang up. Good bye."