It seems the ApacheLounge folks are powering ahead in developing DBD-enabled versions of standard modules. Specifically, Tom Donovan has written modules for DBD logging and vhost-configuration. The latter could be particularly useful, as database-powered configuration is a semi-FAQ in the support fora.
So the portfolio of DBD applications is gradually growing. We now have authentication/authorization, configuration, logging, mod_rewrite (RewriteMap), embedded queries (mod_sql/mod_sqil) and general-purpose forms processing with mod_form.
I’m not trying to follow adoption amongst the scripting languages.