Am Friday, dem 07. Jul 2006 schrieb Shane M. Coughlan:
The GNU GPL went to court twice, once in Germany and more recently in USA. The license was considered valid in both cases. More information about this is available on http://www.fsf.org/news/wallace-vs-fsf and http://www.netfilter.org/news/2004-04-15-sitecom-gpl.html
I think it was 3 times, twice in Germany and the USA case.
See the decision of the Landgericht Berlin, 21. Feb 2006 (16 O 134/06) http://www.ifross.de/Fremdartikel/LG%20Berlin%20GPL-Entscheidung21.2.06.pdf
Sorry, I can't find any English text about it, but it was also about netfilter/iptables.