Another antispam add-on for Movable Type. This one requires the user to wait 15 seconds between reading the entry and posting a comment, which presumably bots don't. But they could, so it's still a temporary/diversification measure.
Also, this requires JavaScript; simply doing that is perhaps as effective as anything else to prevent bots. (I don't know if folks are really scripting IE or Gecko to robopost; again I bemoan the dearth of information on the state of the spamming art.) As Cornerhost users get access logs, though, I would probably throw something together to look in the access log for its data. Having a maximum limit would be good, as the program could tail the log instead of reading the whole day's accesses, but that might annoy someone who takes an extremely long time to write a comment. Only reading the last log file causes a natural limit there too, though, and would be problematic for posting around midnight.
I still think the long term answer is authentication and automatic screening of anonymous comments--giving up the low-barrier discussions--but JavaScript-enabled delay is an interesting tack to take.
