I have spent quite some time figuring out how the GPL has to be interpreted for Javascript in particular. There is no "official" statement (for example by the FSF) on that subject. Some points I find noteworthy:

• Using a Javascript in your website implies "distributing", as the code is transferred to other machines and executed there.
• Concatenated and especially minified JavaScript is not "open source" in the sense of the GPL as it cannot be directly understood or reviewed by a human. De-obfuscation would be required just as de-compilation would be needed for classical binaries. In the GPL, the "source" is "the preferred form of the work for making changes", which the result of minification clearly is not.
• The GPL itself remains vague of what constitutes a "derived work", especially with regards to calling the APIs of libraries.

So, could you (@mattyza?) as the original copyright holder please clarify the following items?

1. When I use FlexSlider in a publicly accessible website along with other (self-written or otherwise obtained) JavaScript code, and that code calls methods of the FlexSlider API, do I need to make this "other" code available under GPL as well?
2. Does it make a difference whether the FlexSlider code is referenced with its own <script> tag, is part of a concatenated or concatenated+minified JavaScript file?
3. Will I need to state on the website somewhere that FlexSlider is used to give you the proper attribution, or is preserving comments in the code sufficient?

Thanks a lot!