The site is being hammered by trackback spam. A lot of it is coming from about a dozen repeating IP numbers, so I've implemented some site-wide blocking to take the load off MT, which seems to chew up cycles blocking spam. This isn't my forte, so if you find that your access has been blocked when it shouldn't be, please drop me a note.
Oh. Wait. If your access was blocked, you won't be reading this, will you?1 Never mind.
1 Unless you move to a different computer, or get a lease on a new IP number, anyway.
For the record, here's what I added to my growing .htaccess file:
<Limit POST GET> order allow,deny allow from all deny from 18.104.22.168 22.214.171.124 126.96.36.199 deny from 188.8.131.52 184.108.40.206 deny from 220.127.116.11 18.104.22.168 22.214.171.124 126.96.36.199 188.8.131.52 184.108.40.206 </Limit>