Found this site with interesting criminal consequences for those who would tampler with the GPL.
http://www.usdoj.gov/criminal/cybercrime/17-18red.htm quote:
Criminal offenses
(a) Criminal Infringement.--Any person who infringes a copyright willfully and for purposes of commercial advantage or private financial gain shall be punished as provided in section 2319 of title 18. either--
* for purposes of commercial advantage or private financial gain, or
* by the reproduction or distribution, including by electronic means, during any 180-day period, of 1 or more copies or phonorecords of 1 or more copyrighted works, which have a total retail value of more than $1,000, shall be punished as provided under section 2319 of title 18. For purposes of this subsection, evidence of reproduction or distribution of a copyrighted work, by itself, shall not be sufficient to establish willful infringement.