Andrew,
you don't have to make S5 presentations by hand. Take a look at http://s5presents.com/ for a RoR implementation of S5. I used this site for my slides as presented at the Boston OpenACS meeting.
I'm sure that OpenACS can do a better job, not because of the technology but because of the quality of its developers. S5presents has to following issues:
* New slides are not added at the end of the list.
* Markup (either markdown or HTML) is not parsed correctly. Experiment and you'll see.
The end result however out shines Wimpy Point.
