i never seen any tute regarding particularly this kindaof navigation… but it´s not that hard.
it is a mc with a big pic that behave based on mouse position with some easing effect.
goto the tutorials page and search for a tute called easing on mouse movement, or so… folow this tute from begining to end, and you shouldn´t have any problems…but if you do, post your question here
You could also do a search around the web for parallax effects in Flash. Parallax is the concept that things closer will move faster than than things further back. In your nav example, the trees.
It’s not only the sideways scrolling, it also moves forward when you click a section, and there are some nice features in each item.
Like it!
Try to find out who made it & ask them