I have been tracking Confluence for a little while now, I have to give credit to their team for a nice product evolution.
In 2.0 in November 2005, they added label or tagging support with cloud display and improved their dashboard display. See their 2.0 release notes.
More screenshots are available in this slide show.
In April 2006, in their 2.2 version, they added support for personal spaces. See the 2.2 release notes.
And, this January, they are adding people directories in 2.3. See their 2.3 release notes.
For those interested in getting in touch with their developers, some of their personal spaces are available online.