On Sun, 2008-11-16 at 20:44 -0500, Neil wrote:

I've noticed that when I go to "Account Info" in Mail.app, and then to
the "Subscription List" tab, Mail.app will spin for a bit, and then
give up, without showing any folders and all the buttons are grayed out.

Does anyone know if this a Mail.app issue or a Dovecot issue, if
there're any work-arounds, and/or if this is something I should be
concerned about?

It's a Mail.app issue. It doesn't really support subscriptions at all.