Upgraded apache from 2.0.59 to 2.2.8 yesterday and my htaccess rules broke. I searched around & discovered that one of the things that changed with 2.2.x was a renaming of the various apache auth modules. Had to put in the following to my httpd.conf to get things to work again

LoadModule auth_basic_module modules/mod_auth_basic.so
LoadModule authz_host_module modules/mod_authz_host.so
LoadModule authn_file_module modules/mod_authn_file.so
LoadModule authz_user_module modules/mod_authz_user.so

Other than that, everything else was easy breezy.