There are specific terms in the GPL[1], and probably elsewhere, that address this issue: [3(a)] Accompany it with the complete corresponding machine-readable s

There are specific terms in the GPL[1], and probably elsewhere, that address this issue: [3(a)] Accompany it with the complete corresponding machine-readable source code, which must be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; It's still open to some interpretation, such as exactly what constitutes "customary media", but probably does rule out the printed on the side of a cow[2] approach taken here. [1] from v2: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html https://www.gnu.org/licenses/old-licenses/gpl-2.0.html [2] http://www.snopes.com/business/bank/cowcheck.asp http://www.snopes.com/business/bank/cowcheck.asp