Comments haven’t worked over at dbmini.us since I upgraded. I searched the WP boards and google, and everything I found didn’t work.
So, I checked the super secret options.php (/wp-admin/options.php). #13 in the list is comment_registration. On mine, it was blank. I changed it to a 0 and voila! Comments work.
If you want only registered users to be able to comment, set that to 1.