Related link: http://www.wired.com/news/privacy/0,1848,49430,00.html

P2P file-sharing fans are finding they’re burdened with a rather unwelcome house-guest. W32.Dlder.Trojan (aka ClickTillUWin), a trojan horse sharing the URLs you visit with a remote site, was bundled with popular consumer file-sharing apps BearShare, LimeWire, Kazaa, and Grokster.