WordPress now supports Gravatars organically (a function of Automaticc, the parent company of the former, having acquired the latter) so I’ve had OTB’s comments section tweaked to support them. So, go sign up for a free one if you want to have a distinguishing logo displayed next to your comments.
(Gravatars are populated based on email addresses so, if you’re using a fake email address on your blog comments for some odd reason, add that fake account to your Gravatar account.)
UPDATE: For the time being, at least, the Gravatars will only display on the individual post page, not the comment dropdown. That’s part of a different module and modifying it is likely more trouble than it’s worth.