Doc Searls posted a entry about Jeremy Miller's MicroID proposal. Its a Microformat as such which allows anyone to claim verifiable ownership of content they generate. You simply hash a communication ID like a email and then hash a URI of where the content will be published. Then hash the two together to generate your unique MicroID. Don't worry theres a generator on the MicroID site.
MicroID = sha1_hex( sha1_hex( “mailto:email@example.com” ) + sha1_hex( “http://website.com” ) );
The important thing to remember is that MicroID is just a way to claim ownership not a authentication. Its also very simple to add anywhere. One of the examples is to put the MicroID in your meta, which I have just done. You can also stick the Microid in a div tag using the class attribute. I'm not so keen on this method, I think semanticly it would be better if it was attached in the id attribute. But I guess it would break if you had more than piece of content from the same author in the page.
I do like the idea of generating a MicroID for every comment which gets published to a blog. Maybe this is one for the Blojsom groups.