if you do not distribute software licensed under the gpl, you do not need to supply source code. this means, if you use gpl-ed software internally, you do not need to inform people of the fact and offer downloads on your website. Unless of course, you were using the software to publish services and it is protected by the "Affero" Clause.
Slashdot Mirror
Try asking those questions to http://pandorabots.com/pandora/talk?botid=c96f911b3e35f9e1 I have not seen buses in London and do not know the right answer, So i do not know if the bot is just bluffing.