Spam - I have received quite an increase of spam comments since I've gotten back (it's up to 4 or so spam comments each day). I've enabled Wordpress' Akismet plugin, which should alleviate the situation significantly.
Copyright - I have noted that a few prominent bloggers have put copyright licenses at the bottom of their comment submission forms. The idea is that, by submitting a comment, you're agreeing that the blog owner has the right to display the comment. It's an interesting idea, and one that I'll think on.