Bumping this one. (I love HTML5)
There are some hurdles which don't allow HTML inputs to be implemented as-is just yet though:
All browsers have their own way of handling these inputs. You will really want to make an example page with all inputs and open them in as many browsers as possible, you'll see the difference. Here I'm not even counting the matter that older browsers will have no clue what to do with these inputs. However, since older browsers will treat the inputs like text inputs, I don't think a major disaster is at hand there. Mobile browsers however, will benefit greatly from these inputs, since they can adjust their keyboard to the type of input.
The following two pages can give you some more information about HTML5 compatibility: