Is it possible to publish content changes using an approval system?  I.e. One user might have the ability to make changes to a Text/HTML module, but the changes aren't visible until they've been approved by a site moderator?  If so, how can such content moderation be completed?  (ideally this would be completed through user roles or similar, so the functionality could be applied to all modules, but initially just the text/HTML module or a good News Article module would be a great start.

Note, I've been advised that this sort of workflow approval process is possible in Joomla.  Our client has a DNN site we've setup for them, but they're considering going to another web developer who has suggested setting up a Joomla site for this functionality.

And if you feel like waiting for a long time, DNN will have this built-in sometime within the next year.  :)

Ventrian's News Articles also has workflow portions.

Jeff