From wikipedia (but it actually happened!):
In August 1999, Unisys changed the details of their licensing practice, announcing the option for owners of Billboard and Intra net Web sites to obtain licenses on payment of a one-time license fee of $5000 or $7500. Such licenses were not required for website owners or other GIF users who had used licensed software to generate GIFs.
Edit:
I am completely opposed to web standards including proprietary codecs. HTML5 should have Theora (or some other open gratis and libre codec) as the standard which all browsers wishing to be HTML5 compliant must be able to handle - this does not stop anyone from using h264 if they wish to. What it does is ensure that the web remains as free and open to use as possible.
If the working groups had plumped for Theora then optimisations and hardware would follow in pretty short shrift. It ain't going to happen and the reasons are commercial - this makes me sad for the future of the web, I see this is a big turning point. Kinda like if the developers of HTML4 had said "we know about the LZW patent but we're going to write in GIF as the standard requirement".
(Incidentally I gather that no image formats were written into the standards before?!).
So do you link to h264 videos from your intranet - want to buy a license for $10k? No? Switch to Theora as the best free alternative. OK, now none of the browsers support your video format natively. Congratulations you've been screwed again by MegaCorp.