There is a super easy solution for designer to build a parallax website. Adobe Edge Animation http://html.adobe.com/edge/animate/
Designer can set the animation in the timeline window. All skills and design experience are very similar to doing a Flash animation. The difference is that we can use Adobe Edge Animation to bind mouse event to control the timeline and the final export result support the modern browsers including mobile devices. What we need is just spend time to make a perfect (Flash) animation in Edge Animation. Export. Done.