This cropped up in a post about the latest improvements to Typepad:

> Improved comment experience > [![Comment-form-icons-typepad]( "Comment-form-icons-typepad")](http://everything.typepad.com/.a/6a00d83451c82369e20120a5d7c8a1970c-pi) > Based on some impressive performance on the beta blogs, we have added a few popular social web icons — TypePad, Facebook, and Twitter — on the comment forms. We tested this design in beta for a few weeks and saw a dramatic increase in the commenting activity. By encouraging people to sign in and become a “real” person, we have seen a significant increase in comments. 
If that’s true, that’s very interesting. The ability to sign in with another system, pull across profile images and set some sort of link between your activity across the web encourages engagement? That’s pretty significant for anyone working in community development.
And Dave Winer was musing on the [importance of Twitters user icons](http://www.scripting.com/stories/2009/09/18/theRssChannellevelImage.html) just the other day…