I had a problem where I was trying to construct audiences in MOSS with members based on certain Active Directory groups, but I had a handful of groups that did not appear in the "browse" dialog on the Add Audience Rule page. It turns out these groups were empty, and that the group list is populated by reading the groups each user is a member of during the profile import. This dialog does NOT contact AD.
I added an account to the groups in question and repeated the profile import. Voila--the groups appeared in the browse dialog.