All this HTML5 form malarkey is all well and good. There seems however, to be two things that put a serious dent in our ability to use them: disparity between how supporting browsers implement the features, and how to deal with browsers that don't support the features at all.
If you need to support some of these features in older or non-supporting browsers then consider Webshims Lib, which you can download at http://afarkas.github.com/webshim/demos/. It is a polyfill library written by Alexander Farkas that can load form polyfills to make non-supporting browsers handle HTML5 based form features.
Note
Exercise caution with polyfills
Whenever you reach for a polyfill script remember to consider carefully. While they can be very handy, they add weight to your project. For example, Webshims also requires jQuery so there's yet another dependency needed if you weren't using jQuery before. Unless polyfilling older browsers is essential, I steer clear.
The handy...