suraj.sun quotes from a CNET story: "A federal court judge has likely dealt a death blow to LimeWire, one of the most popular and oldest file-sharing systems, according to legal experts. On Wednesday ... US District Judge Kimba Wood granted summary judgment in favor of the ... [RIAA], which filed a copyright lawsuit against LimeWire in 2006. In her decision, Wood ruled Lime Group, parent of LimeWire software maker Lime Wire, and founder Mark Gorton committed copyright infringement, induced copyright infringement, and engaged in unfair competition. 'It is obviously a fairly fatal decision for them,' said [an industry defense lawyer]. 'If they don't shut down, the other side will likely make a request for an injunction and there's nothing left but to go on to calculating damages.'"
The article notes that LimeWire is used by nearly 60% of the people who download songs.