ok, first of, media like music and pictures/textures is not software code, an thus cannot be GPL.
that is why i think we/you shood use the CC liense. http://creativecommons.org/
http://creativecommons.org/licenses/by-sa/3.0/
this is a good licens if you ask me, this is not the howle license but a summery..
this is the license http://creativecommons.org/licenses/by-sa/3.0/legalcode

Btw hi again!

we (at least some of us (hi Div)) are painfully aware of this, however the CC licence cannot be applied as its incompatible with the licence most of the current content is released under.