Demonstrate where the FSF has. The thing about copyright infringers of GPL code is that it's much cheaper to just give up the added code than pay possibly millions in damages at court. Luckily for these copyright infringers, free software gives them that option, which so far everyone has taken. In the proprietary world they just have to pay up.
Linux's Hit Men (Forbes)
http://www.forbes.com/2003/10/14/cz_dl_1014linksys.html?