Richard, this bug was filed quite a while ago. I really wanted to just reply on your blog, but you don’t allow “anonymous” comments.
I don’t use LJ, so I’m not familiar with how they handle comment spam. Is there a capability like the Akismet plugin I use for WordPress? I don’t see more than one or two spam comments every couple of months, and they’re always held in a moderation queue for me rather than posted straightaway.