Comments should be turned off after a certain amount of time after the article has been published; perhaps this could be a scheduled action? Most comment spam is added well after the article has been published, and because I don’t think there is a notification mechanism for comments, the only way to find out if there’s been comment spam posted is to periodically check the comments and clear them out.
At least if the comments were to automatically lock after a period of time set by the administrator, there would be fewer opportunities for spam.
