webfinger - Project Hosting on Google Code

I had forgotten about this...

People have been trying to use URLs as identifiers for people (as OpenID does), as it has great readability/discoverability properties, but this effort has largely failed because of UI/UX design failings, user confusion about URLs, etc.

It's now increasingly accepted that email addresses would be good identifiers for people (since that's what people are used to already, and have on business cards and in their addressbooks, etc.), but we're back to the original problem that email addresses are write-only.

If I give you my email address today, you can't do anything with it except email me. I can't attach public metadata to my email address to give you more information.

WebFinger is about making email addresses more valuable, by letting people attach public metadata to them. That metadata might include:

public profile data
pointer to identity provider (e.g. OpenID server)
a public key
other services used by that email address (e.g. Flickr, Picasa, Smugmug, Twitter, Facebook, and usernames for each)
a URL to an avatar
profile data (nickname, full name, etc)
whether the email address is also a JID, or explicitly declare that it's NOT an email, and ONLY a JID, or any combination to disambiguate all the addresses that look like something@somewhere.com
or even a public declaration that the email address doesn't have public metadata, but has a pointer to an endpoint that, provided authentication, will tell you some protected metadata, depending on who you authenticate as.
... but rather than fight about the exact contents of that file, WebFinger is about making that file discoverable at all. The community can explore and innovate within that discovery file later.