Hm, I hadn't heard of S5. I particularly like the ability to toggle
the display between slide/presentation and single-document mode.
I am somewhat suspicious of the javascript dependent implementation
however; it seems to mostly work but gives a few wonky behaviors in
Mozilla 1.7.5.
A single-file standard data format for an entire slide presentation is
also a very good thing, but on cursory inspection, the markup looks
fairly complicated. Doing the whole thing in Emacs is probably
doable, but most people aren't going to want that. Some sort of
simple UI like WimpyPoint is probably very necessary.