If upheld, the decision could lead artists, record labels and movie studios to cast new legal strategies that they have until now been reluctant to try, including bringing lawsuits against individuals who copy unauthorized works over Napster-like networks.

This could cause a whole lot of people to become very unhappy.

Yeah. Mostly RIAA and MPAA people. It's easier for them to target a single point of distribution. What they've been trying to do is tantamount to shutting down an entire fleamarket because some people at the fleamarket are selling pirated items, never mind the fact that there are also a lot of people at the fleamarket *not* selling pirated items.