When I read the Apache docs way back when, I got the impression it was pretty much SOP. Of course most of those docs were probably written by mass web hosts.
Reason I need it is I'm trying to set up a WordPress multi-site instance. Partially as a long-term experiment, but also to learn how it works so I can pitch it to some potential clients.
What would be really nice is if WP could handle both subdomain- and subdirectory-based hosting in one installation.