http://blog.stevensanderson.com/2012/08/01/rich-javascript-a...
we use this technique at food52.com, e.g this content page cached uniformly, login system, recipe saving widget, comment system all done in ko.
http://food52.com/recipes/22888-yotam-ottolenghi-sami-tamimi...
more interactive / sophisticated uses of ko coming in our new shop soon for the cart functionality.