Whoops!
(I think that's big enough)
Yep I've just found out that comments has been blowing up on my blog. At some point (I think when I migrated from 1.7 to 1.8) I somehow lost a permission in the ACL.
To everybody who has attempted to write any posts, I can only apologise, but they are working now.
Feel free to flame, just don't abuse :)