I've noticed that some comments are posting and some are not--I've run a few tests and cannot figure out the problem. Until them I'm turning off comment moderation and turning on word verification--that will be a temporary fix until I hear back from Blogger Support.
Update: OK, I republished the entire blog and it looks like things are going ok now. I'm going back to comment moderation (with word verification off) and so far it looks like it's working. Cross your fingers. I'm really not deleting your comments! I haven't had to do that in months, and that was just for repeated foul language and personal attacks.
If it looks like more comments aren't getting posted, though, I'll switch comment moderation off.