Duncan Riley> After changing from MT to WordPress on 3 November this year I shortly thereafter deleted the mt-comments.cgi file from the MT installation.
This is the result:

46601 404 document not found hits for the month of November with virtually all of them attempted hits on the mt-comments.cgi file. That’s 46601 attempts at posting comment spam on the Blog Herald.

The following points arise:
1. MT Blacklist, although still often letting through 100′s of comments daily was blocking the bulk on them
2. Comment spam is even more out of control than I had imagined, although I’m happy to say but since changing to WordPress aside from the stray 1 or 2 I haven’t had the same problem, without having to use a registration service such as TypeKey
3. I may potentially have a record on my hands?

If you’ve had similar problems or can beat the number let me know!