Interesting site update: we now support Gravatars. To have your gravatar shown in your comments (see my comment below), sign up on Gravatar.com and create an account.
Signing up for a gravatar.com account is FREE, and all that's required is your email address. Once you've signed up you can upload your avatar image and soon after you'll start seeing it on gravatar enabled weblogs!
Gravatar.com is run by the same people who write WordPress, by the way.
Update: we accept gravatars with a rating up to 'PG':
PG rated gravatars contain may contain rude gestures, provocatively dressed individuals, the lesser swear words, or mild violence.