The following KB articles relate to this topic:
A wonderful new addition to the responsive template is the ability to customize the website's footer area into a "super footer". The footer is not a content block, but rather an editable region of the website's main page. To edit, simply open the Template Settings on the main page.
Nearly all of the available content classes can be added to the footer, including column layouts, text areas, lists of pages, images, and more.