[Tip o' the hat to Dave Farber's IP list] A detailed and useful EFF report on Comcast's use of packet forgery and other techniques to interfere with P2P traffic is here. The report says that the consequences of packet forgery include:
Comcast's interference is potentially troubling as well to the extent it may hobble potential competitors deploying next-generation video distribution services. BitTorrent Inc., for example, now distributes films under license from Hollywood movie studios and thus competes with Comcast's cable TV products. Similarly, Vuze, which recently filed a petition with the FCC for rule-making regarding Comcast's interference practices, also sells downloads from a huge library of licensed content, using BitTorrent as a distribution mechanism. Other companies and products, such as Joost and Miro, also rely on P2P protocols that are similar to those that are being impeded by Comcast.... [footnote omitted]
Writing on Alternet.org, Annalee Newitz says about Comcast's interference:
...No laws guarantee network neutrality online, so Comcast is free to engage in network prejudice. The company can block any service it wants, especially if there's a financial incentive. Certainly, consumers can choose to go with another Internet service provider, and I hope they do. But in the future, market competition may not be enough.
If Comcast blocks BitTorrent, then another company might welcome BitTorrent traffic but block my favorite game services. Internet service will become like cable TV, where getting the full range of channels is incredibly expensive. Except it will be worse, because the Internet is a far richer and more diverse place than cable TV. Selectively blocking the Internet is like selectively blocking expression itself.