Licensing

Doesn't the GPL primarily determine the rights of distribution, not terms of use?

Looks like your question is related to this one:

http://www.activewidgets.com/javascript.forum.6000.3/incorrect-gpl-interpretation.html

I guess what matters is GPL exact text and not my interpretation of it. I was asked many times to provide one sentence simple 'black-and-white' answer when somebody has to use commercial license over GPL. I believe my recommendation is safe to use but it is intentionaly oversimplified and missing all shades of gray and black holes of 'real' GPL (which you should consult together with your lawyer in case you have doubts).

Obviously choosing GPL for a client-side JavaScript library was very bad idea. Now I would rather recommend using commercially licensed code than going deep into how GPL is supposed to work in this case.