Whereas CommentLuv and KeywordLuv promote your blog, a gravatar promotes your identity.
Looking back at recent articles on this blog, here are 9 gravatars that stand beside people’s comments:
Once you sign up for an account and upload a photograph to represent your headshot or your logo, your gravatar will be shown beside every comment you make on WordPress blogs, comment sections powered by Disqus and Intensedebate, and even Mailchimp newsletters.
With all the spam you receive nowadays IT is indeed difficult to distinguish the real comments from the fake ones. A gravatar often helps in the qualification
If it’s from AutoMattic, it’s going to be an exceptional idea. Gravatar, wordpress…. just the tip of the iceberg from what’s coming from these guys (their founder is 27 years old, btw).