Hm, no? That's the url, bam. I didn't actually read the site, just looked at the code and the colours : )
I wondered. Earlier I saw this thread and thought, an image is stuck in px...
I don't want to say that. I keep thinking it probably can be done, but it shouldn't be brittle.
There's some CSS3 stuff coming out like background-position which can do more than the old background-position, and the gradients have start and stop properties which can be set in %s. In fact, now that I think of it, I've seen Lea Verou do % background colours by taking CSS gradients and stopping them in a severe way, so that it's not really a gradient but a line. I forget now what exactly she did, but I can dig it up. She uses it to make the CSS patterns on her site. Of course, this is CSS3 so we'll need to think of something else too. What's cool about the gradients is, they are applied onto "background-image" so you can start with a real image for non-supporting browsers and then override with the gradients. Browsers who support the gradients won't use the image.
*Edit I was thinking of stuff like this http://lea.verou.me/css3patterns/ but I notice they're making px-sized gradients and repeating them like images
The bam site is using a div called "push" which is a popular sticky-footer solution floating around on the web. I forget already what the div does, but Paul's various sticky footers don't require the extra element. I also notice they had a clearing div too. Tsk tsk.