very nice! you may want to consider doing these transitions with CSS3 and falling back to javascript top/left animations because they are optimized for mobile. The transitions lag a bit on my iphone.
also it would be nice to have a fixed header, like a menu navigation. you could have the animated content be local to a div with an overflow: hidden attribute, as opposed to moving the entire page.
Your suggestion for the CSS3 is great, I'll definitely toy around with it in the next few days.
Secondly, Parallax.js can already do this. It simply moves around the divs you feed it, which can be tiny or full screened! This allows you to throw your own header on the top, or, if you like, a same parallaxing div in the center of your page.
also it would be nice to have a fixed header, like a menu navigation. you could have the animated content be local to a div with an overflow: hidden attribute, as opposed to moving the entire page.
great work!