The list of brand-name OpenID adopters speaks for itself, with — by some counts — now more than 1 billion functional OpenIDs on the open internet, but for the internet identity movement this quote from Kim Cameron, Microsoft’s Chief Identity Architect, is rather significant:

In the last year, OpenID has without doubt become the most widely adopted system for reusable internet identity.  Adoption by destination sites continues to grow dramatically: approximately 50,000 sites as of July 1, 2009.  The big Internet properties like Google, Yahoo, AOL, MySpace, and Windows Live have become (or are becoming) OpenID Providers.   As a result, the vast majority of the online US population has an account that can be used to log in at the growing number of destination sites.

What a little URL could do …