I’ve opened up the ability for users to leave comments to make it less restrictive, mainly an account is no longer required to post a comment.
Your first comment will still need to be moderated, but after that they should be instant unless you include any links.
Fighting spam is always a fine line, but I’m actually less worried about spam than I am malicious links. So, we’ll try this and see how it goes. If it gets out of hand I may have to lock it down again. Until then, happy commenting!
Update 12/15/2012: I’ve reverted it back to needing to log in to comment. All I’ve gotten is an enormous amounts of spam in my e-mail!