Great to see big (more like huge) brands taking the One Page route. The Mountain Dew site showcase masterful AJAX loading while rearranging the content in the page.
This website has unfortunately been redesigned or gone offline, so I have removed the direct link to it. The screenshot below hopefully preserved enough of the design but if you are really keen to inspect further, try this Archive.org link. FYI: the site was first featured on 21 August 2012.