Google re-introduces finger protocol, dubbed as WebFinger (aka Personal Web Discovery) over HTTP. The idea behind WebFinger’s about making email addresses more valuable, by letting people attach public metadata: 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) etc. ... 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. Google points out that your Gmail address could soon be your ID.

More info: WebFinger