There have been a few blog posts recently that mention Confluence on the topic of using wikis for documentation. For anyone currently exploring using a wiki for documentation, you might start with one of these blogs:
There’s Kola Oyedeji’s Coolskool blog, called Using Wikis for Documentation.
On Ludovic’s weblog there is a post about Confluence (and Jira) for Tracking and documentation tools.
SaaS-Man’s Documenting Web Services (hilarious headshot, by the way) says that they’re currently evaluating documentation tools.

Documentation Tools...