HTML 5 is cool, but it's hipster, many browsers don't work with all of HTML 5 yet.

Here is what does work in the browsers:

Here is a breakdown of input types that DON'T work yet:

Google Chrome (20.0+) :
type = "datetime"
type = "datetime-local"
type = "month"
type = "week"

Firefox:
type = "date"
type = "datetime"
type = "datetime-local"
type = "month"
type = "week"

IE:
type = "date"
type = "datetime"
type = "datetime-local"
type = "month"
type = "week"