As Simon pointed out, the CSS @font-face declaration can be used to implement traditionally non-web-safe fonts on your site. If you want to try it yourself, definitely check out Paul Irish's now famous bulletproof font face implementation, which links to FontSquirrel's font file generator. It's now supported cross-browser with the right implementation, although with most fonts you'll have to deal with licensing, and consistent rendering is still an issue. The site you asked about though uses Typekit, one of several new services that will host and serve font files for you (for a fee), and offers you an easy implementation that masks the complications of @font-face. Google's Font API is similar, although it's free and only hosts/serves a small selection of free fonts. Also, non-native alternative techniques for embedding fonts have been around for a while (although they wouldn't be indicated in the CSS), see cufon and sIFR.