@Brian Layman - For the record, the assumption you make here:
I would almost guarantee that the “I run my 6 sites on WordPress.” commenter was thinking of 6 blogs, and not a single mu install with six mu “sites” each running a single “blog”.
...is incorrect. I use the word blog at all only because it is still the common parlance. If you look back through the IRC logs you'll see me lobbying for changing Blog to Site and Site to Network in the parlance of MU. Since most of my job right now is in making WP core sturdier as a CMS, I can guarantee that I'm not just thinking of online journals, but of full-fledged sites in a network of sites on one WP install.