Due to an increasing amount of spam comments being posted to old blog posts, I have set the blog service to automatically lock comments to blog posts older than 3 weeks months. I felt 3 weeks months was about right to at least allow for conversations, if not let me know in email or comments to this post.
Spammers and comment bots ruin it for everyone unfortunately.
Sincerely,
Shaan
Update 02/11/10 I have updated the script for auto closing out comments after 3 months.