Hi, Just tried this on 0.11rc2, as far as I can tell, it didn't work:
Installed the plugin, enabled it. set the handler to first in the list, added the [privatewikis] section, and protected a couple pages. I then restarted the server, gave myself permissions to one of the pages, and created the "protected page" I gave myself permissions to. Went to another machine, accessed the trac anonymously, and was able to navigate to the page. No errors in log.
Trac 0.11rc2, apache 2.2 python 2.5.2, mod_python under windows. Using SSPI authentication via windows domain controller. Sorry if there is already a ticket for this, clicking your existing tickets comes up blank.
feel free to email me, I know there aren't many details. I can add some debug code or something.