Peter,
I agree with you about Plone. I spent an afternoon a couple of weeks ago going through a basic OACS setup with a friend who wanted to set up a community site ( http://www.newbeekeeping.org/ ). When I saw him yesterday I find he'd used Plone. Why?
1. It does exactly what he wants straight out of the box.
2. Its UI looks very good with minimal modification required. Basically a logo and footer.
3. It has a neat text markup which is a bit like a wiki on steroids.
4. He can import Word docs and it turns them into web pages (he is a Lotus Notes man).
5. He has the whole thing hosted for $60/year. http://www.zettai.net/Members/george/plonehosting.blog/view
OACS for all its strengths (and they are many) can't really beat that.
- Steve