P2P networks make up majority of Internet traffic
It turns out that P2P file sharing programs may be eating up much more bandwidth than originally thought. Simply adding up the sizes of files being traded over P2P networks isn't enough according to one researcher, you have to include all the messages necessary to maintain the networks themselves.
The big deal is that we haven't been measuring the right things when it comes to bandwidth use. P2P networks, it turns out, are very messy. They have to find and then connect to four or more other computers directly, constantly send out repeated "I'm alive" messages to all of them, and send out and process search requests. In the other direction, they have to field connection requests from other computers, offer up search results of your shared folders, and generate other computer communication best described as "network chatter." The traffic increases geometrically for those who have programmed their software to act as a "supernode."
The original research paper
(registration required) estimates that up to 60% of all Internet traffic is generated by P2P networks, which may put the business models of some ISPs in jeopardy. Thanks to Shacknews
for the tip.