Along with building their own service (which now includes access to 1, 500 fonts with another 1, 000 classic fonts soon to come through an agreement with Monotype) Typekit has also been collaborating with Google for the last couple of years on its web font APIs.
But HTML has at last evolved into HTML5 (and CSS3), which allow web designers to use custom fonts, gradients, rounded corners and transitions, among other uses.