As many have pointed out, the 9th Circuit upheld the Grokster decision yesterday. The opinion is a good read and as others have pointed out definitely shows a keen understanding of the technology and the differences between the various flavors of P2P.
I particularly like this paragraph towards the end of the opinion:
Further, as we have observed, we live in a quicksilver technological environment with courts ill-suited to fix the flow of internet innovation. AT&T Corp. v. City of Portland, 216 F.3d 871, 876 (9th Cir. 1999). The introduction of new technology is always disruptive to old markets, and particularly to those copyright owners whose works are sold through wellestablished distribution mechanisms. Yet, history has shown that time and market forces often provide equilibrium in balancing interests, whether the new technology be a player piano, a copier, a tape recorder, a video recorder, a personal computer, a karaoke machine, or an MP3 player. Thus, it is prudent for courts to exercise caution before restructuring liability theories for the purpose of addressing specific market abuses, despite their apparent present magnitude.
The decision and a comprehensive round-up can be found at The Importance of... (via Trademark Blog), and some interesting analysis by Eugene Volokh and Lawrence Lessig.