Great writeup, thanks!

One small correction: there are a *lot* more than 6 Plone hosting companies out there — http://plone.net/hosting-providers has the definitive self-service listing of them, over 100 in all. Many of these folks also offer consulting services, but some are pure hosting plays.

Like you, I expect to see more soon.

Also worth noting is a still-in-development tool called Xarope that “is designed to be an easy way to convert any server into a virtual server to offer Zope/Plone hosting. It’s based on Xen.”