Apparently CacheLogic based most of their conclusions on data collected from a European "tier 1" ISP. However, another study by Sandvine found regional differences in file sharing networks. Europe and the US don't have the same file sharing patterns, or even popular file sharing programs.
http://www.sandvine.com/solutions/pdfs/Euro_Filesharing_DiffUnique.pdf Of course, there is always CAIDA's data. Peer-to-peer analysis is on their long range plans. http://www.caida.org/projects/progplan/progplan03.xml
