Whither Site Maps?

Today Lorelle talks about The Art of a Good Site Map, discussing what is an often-neglected component on blogs (including this one). Putting together a good subject-based site map is something I’ve been pondering for a while, but have wondered if folks would use it any more than the tagging system.

Site maps vs. tagging: is it analogous to e-mail? Are site maps for the people who like to categorize their e-mail into hundreds of very subject-specific folders, and tagging is for folks who prefer to dump their e-mail into one archive and then search?