Bulletin board readers are accustomed to using icons/avatars to represent their identities in online discussions. But because blogs are scattered to the wind across a bazillion servers, this capability is not generally available on weblogs. What is consistent across your participation in multiple blogs is your email address (even though it’s never displayed publicly, it’s usually required for comment posting). Gravatar leverages this consistency by letting you create a (free) account with them. Your avatar then appears automatically when you participate on any Gravatar-enabled blog.
Auttomatic (the hippy/corporate entity behind WordPress) has acquired Gravatar, giving the the service the juice it needed to keep performance up. I’ve enabled Gravatar on Birdhouse — set yourself up a free Gravatar account and watch all of your historical posts on this site grow a magic
Aside: WordPress now powers almost 1% of the web. Don’t tell me it’s just a blogging tool.