It's coming soon. See Jay's post for more details. If you thought the first release was groundbreaking (which it was), you'll be floored by this version.

The next version of MT-Blacklist addresses the comment and rebuild slowdown as well as other issues from the v1.0 release. This is not just a bug fix release, but a conceptual redesign of the URL filtering function in v1.0. The model will now more closely resemble that of an anti-virus solution, with active blocking (as in v1.0) and the ability to clean old comments of banned URL's. The cleaning and rebuilding is a change from the URL filtering in v1.0.

In the next version everything on your blacklist is blocked as it is in v1.0. If a new spam that is not blacklisted comes with v1.5 you have the option to add it to the list, delete it (and rebuild), plus find and delete all existing comments containing the same banned URL or from the same IP address. In one step you catch and remove new spam sources if you have 50 or 50,000 comments. There is not a performance penalty on comment posting or rebuilds because the URL filtering, which caused those slowdowns in rare cases, is replaced with an blogger controlled cleaning function. It's a revolutionary change in your ability to manage comments and trackbacks.

I need to move this to the sidebar, but my Wizbang Blacklist Add-On Listing (and archive of all posts on the subject) is available here.