I have been testing impress.js on my webpage to day. I think it is cool and will nicely replace prezi for me. But i wished it didn't have one feature. It replaces the default html / css way of working with its own absolute positioning system.
I will do to things to investigate if i should stay with impress.js
See if it is possible to disable the prezi positioning.
See if any of the other js alternatives does use standard html/css for layout.