An important distinction between a "cosmetically responsive website" and a fully responsive site. While media queries are great for changing things visually, they don't change content. i.e. Users approaching a site from a handheld perspective will be there for a different reason than ones visiting the site on a desktop and therefore should optimally be served different content, not the same content with a different interface.
It would be very helpful to have data as to what users do online on their mobile phones. If anyone has some good resources, please post them.