Moveable Type seems to have taken a very drastic step to thwart comment spam. I am really surprised they went this route, we dismissed this technique right off as it denies the linky goodness to legitimate comments. As Matt said, "they’re throwing the baby out with the bathwater."

We’ve already put some comment spam prevention functionality into WordPress and we have a lot more ideas we’ll implement before we do something like this.

My own experience has been that with just the use of a blacklist, I’ve caught 95+% of my comment spam. This may not be scalable indefinitely, but I could always go to moderated comments or (in the future) a baysian filter or…