I didn't like having to manually moderate all comments, so I've installed a new little plugin that should fix it for me. Below the comment text box, but above the 'post' button, you should all now see a text box. Above it, it says to enter the word 'hello' in the box below.

Voila -- all you have to do is type hello and your comment will go through and be published immediately.

Let me know if you have any issues...