Per demonsurfer's help at Jay Allen's MT-Blacklist forum, I was able to fix the 'human error' that screwed up my installation/upgrade of MT-Blacklist....
MT-Blacklist -> MT-Blacklist v2.03b feedback:
Delete all the MT-Blacklist related files from your server, then log in to your database and remove the tables that start with mt_ext_bl_xxxxx (usually there are seven of them). Next remove all rows in the mt_plugindata table in your database that mention MT-Blacklist. Once those are gone you can then try installing MT-Blacklist from scratch as a fresh installation (and run mt-bl-load.cgi).
....which is a good thing because in the few hours that MT-Blacklist wasn't working, I got about 15 comment spams (in old threads). Bleh.
