Since this isn't available in 2.2.17, I figured it would be classified as a third-party mod.
The author says he has one that works with 2.2 and has made the code available for download. Curious if anyone has given it a shot on 2.2 yet.
Looks like ASF is waiting for 2.4 to make it available? Be interesting to play with. :)
In 2.2.17 there is mod_authn_dbd.
In 2.4 there is mod_authn_dbd and mod_authz_dbd. I guess you should try Apache 2.3.11-beta from our download page ;) http://www.apachehaus.com/cgi-bin/download.plx#APACHE23
I am in possession of a mod_authn_mysql as well, still need to test it which will happen this week.