http://v3.espacenet.com/searchResults?locale=en_EP&IN=eh...
Specifically take a look at these claims: http://v3.espacenet.com/publicationDetails/claims?CC=US&...
I'm not really sure whether those are actual patents or patent applications, but even in later case the chance of them being rejected are very low.
For instance, this paper I wrote in 2002 uses techniques which overlap with their claims: http://www.springerlink.com/content/ujrmkgp929v6je7p/
I'm sure there's a mountain of other prior art covering the concept. It isn't novel to anybody with half a brain. I was streaming audio in the 90s and clearly remember thinking about a p2p network then, because of the expense and legal threats I was receiving. All I wanted to do was enable football fans living abroad to listen to the local radio station on match days.. I thought I was doing the BBC a favour by extending their broadcast range! Yeah, I was just a naive kid. :)