While upgrading apache 2.0 -> 2.2 I found that two configuration options have changed:
AuthAutoritative->AuthBasicAuthoritative(needs to be set to Off for mod_auth_pgsql to work).AuthDigestFile->AuthUserFile
Plus there has been a log of changes in apache2.conf. I looked at the changes we made (keeping /etc/ in SVN comes in handy, in spite of occasional pain) and pasted them to the vanilla apache2.conf that came with 2.2.