Yeah, according to the letter of the GPL (and IANAL), by using the framework on a website, you're not actually distributing it -- so you don't need to release the code. You're only distributing the generated output.

This is one of the "loopholes" that RMS was talking about closing recently -- you can use GPL'ed components to provide web services in a proprietary system, because you're not actually distributing them. I'm not sure how he's planning to do it, though.