the licensing of modules, components, addons, or whatever they're called by various cms packages is a pretty heated debate in some camps.
some projects, such as mambo/joomla promote the existance of "commercial" modules and say you can license them any way you want, even restrictive commercial licenses; one of those goes so far as to have commercial third party developer(s) on the development team dictating what features to include in the distribution and which ones to leave out (thus opening up a potential commercial market for those left out; which in my book is a conflict of interest).
while others, like textpattern, promote the fact that modules should be gpl licensed. textpattern's site references relevent portions of the gpl here:
http://textpattern.com/faq/51/what-license-does-textpattern-usethe word i've received from the licensing gurus at the fsf (on two separate occassions over the last four years or so) is even stronger than the textpattern opinion (above), citing that modules, components or what-have-you for a gpl licensed cms (such as mambo, joomla, the 'nukes', website baker, textpattern, wordpress, etc...) *must also* be licensed under that license. period. which is exactly how i interpreted the gpl before their replies to my queries.
if you don't want the gpl to apply, then don't distribute (i.e. use for yourself on your own site only) at all. if you want to sell them, the buyer(s) must receive it under the terms of the gpl (including distribution rights).. alternatively, you could sell and assign copyright to a single buyer (and then if they distribute, it must be gpl licensed.. and remember that once copyright is assigned to someone else, you, yourself, cannot resell it or something based upon it).
unfortunately, the only one that can enforce the terms of the gpl is the copyright holder, meaning mambo and joomla users are basically sol because their development teams don't' give a rat's behind about the gpl and how it is supposed to apply to addons to their software.
so, i am wondering what website baker's "official" opinion or stance is regarding the licensing of modules. do you require they be gpl (or compatible) licensed? do you suggest or recommend a free software license? or don't you care at all one way or the other?