Norm,
I'd recommend registration, too. When I put up docbook.xmlpress.net, I left sign-up open, and it wasn't more than a month before we started getting spam (and that was on a site that had about 5 active users and not a lot of content at the time:).
BTW, in your search, did you see any wikis that could import/export XML? That might not be a top consideration, but it would be nice to be able to get DocBook into and out of the wiki without too much trouble.
Dick Hamilton
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XML Press
XML for Technical Communicators
http://xmlpress.net
(970) 231-3624
