I've turned on the requirement that you have to provide an email address when leaving a comment. If that stops you from commenting the fix is to delete the cookies you have from scienceblogs. PZ Meyers has more on this and other bugs.
If you have any other bug reports or suggestions for improvements, leave a comment.
I don't think turning email on for comments is going to work--you can just put any address in there, even a fake one, and the comment is still published.