For the past several months, Comcast has been covertly sending commands to your computer that tell it to stop receiving information -- especially if that information is coming to you via BitTorrent, Gnutella, or other file-sharing applications. In May disgruntled Comcast users started posting on message boards about how BitTorrent and Gnutella weren't working for them anymore. So researchers at the Electronic Frontier Foundation, along with an AP investigative journalist, started running tests on the Comcast network, using software tools to examine what exactly Comcast was doing to BitTorrent.
What they found was disturbing. Without telling customers, Comcast had begun a secret program to send automatic reset commands to customers'
computers if they were using BitTorrent, Gnutella, or a few other programs. None of these programs are illegal. Moreover, Comcast had sold its services to customers without informing them that this popular Internet software wouldn't work on its network. And Comcast is still doing it.
Taken from Annalee Newitz, AlterNet