2007/9/19, Mark Clements gmane@kennel17.co.uk:
I am not sure whether private modifications that are only used internally are required to be released to the public under the GPL. Simetrical seems to imply not, whilst Voice of All's reply seems to imply that you do. I am also unsure as to whether using modified code on a public sites constitutes public distribution. I guess you should consult your lawyers on that one (though I guess you already have...)
You're not legally required to release anything if you're using a (modified) GPL'ed program to power a public website: http://www.fsf.org/licensing/licenses/gpl-faq.html#UnreleasedMods
However, as you say, it would still be the right thing to do, just in order to get that warm fuzzy feeling of having given back to the community that gave you so much that you could build on. :)