By registering, you can secure a username for the comments section, so no one can pose as you. There will probably be additional features down the road as well.
Your email address will never be shared and will only be used for what you give permission. Your password is irreversibly encrypted in a secure manner, so even if attackers got access to the database, there wouldn't be any need to seriously worry. (I am aware of the weaknesses of SHA-1 and will upgrade to a more secure algorithm eventually.)
Really though I don't care if you register or not. I dislike the blogs that demand an email address to post a comment (I always put not_necessary@hotmail.com), and allow just anyone to piggy-back on your site with URL linkbacks (though it's something to be taken advantage of), and then to top it off want a captcha. Well, with mine, passers-by need only supply a display name (default Anonymous), their comment, and pass a simple captcha test. If you register, you only need to enter your comment, with a few optional checkboxes such as post anonymously and other features as they come.
