Thanks for the answers.
For Justin
In principle your idea is nice, but I foresee it to become unworkable when one wants
to add more validation rules to the input field as in you last example
<input can-value="name" validate-required validate-length-gt="3" />
I took air_hadoken approch and put the validation rules on the model which
is much cleaner as the validation rules and validation messages are all in 1 place.