Technorati reads the FOAF file from your blog and creates a profile. Your picture from your FOAF file and a link to your profile shows up when you appear in people's cosmos listings. A good reason to get a FOAF file. TypePad has FOAF built in. If you want to build a FOAF file, you can go to this foaf-a-matic site (thanks for the link Sifry) and make a FOAF file. Put the FOAF file on a server and point to in from your blog with a link tag like this:
<link rel="meta" type="application/rdf+xml" title="FOAF" href="http://joi.ito.com/foaf.rdf" />
FOAF stands for "Friend of a Friend" and it is a project to create a machine readable format for putting information about yourself and your friends on web pages.
Here's Marc Canter's profile
Update: As Dave Sifry says in the comments section, you must get an account on Technorati and "claim your blog" before it will make a profile from your FOAF. You can do that here.