Pre-OpenWRT days I was maintained a Linux distro ISL3893 that ended up in court in Germany, the first GPL enforcement:

http://isl3893.wikidot.com/

"17 apr 2004 — GPL testing in court by the Netfilter/Iptables team, due to refuse to give source code of the Sitecom WL-122 (isl3893 based!). In the same time, some source code has appeared on the webserver of Sitecom."