HaloScan, the service which currently hosts our commenting system, has disabled the "edit" function, which means that we cannot moderate comments as we'd like.
I'm looking at alternatives (Disqus, Intense Debate, etc), and will have a decision soon. Unfortunately, this means that, for the time being, some comments will not be approved. These will include comments with links to commercial sites (as opposed to other blogs).
I am truly sorry for this, but it can't be helped.
If you'd like to comment on a post, and aren't sure whether it meets the guidelines, please send it to me via email with "Comment" in the subject line, and tell me which post you're commenting on.
Thank you for your patience!