When Google announced Google Buzz earlier this week, the company made it abundantly clear that it was interested in Buzz being as open as possible. Looking at the Google Buzz API page, you'll see that support for Activity Streams, AtomPub, OAuth, PubSubHubbub, Salmon and WebFinger are things that are "coming soon."

What all of this means is that Google is working to make Buzz content something that can be used in as many services as possible, while letting as many services as possible come into Buzz.

"The idea is that someday, any host on the web should be able to implement these open protocols and send messages back and forth in real time with users from any network, without any one company in the middle," says Google software engineer DeWitt Clinton. "The web contains the social graph, the protocols are standard web protocols, the messages can contain whatever crazy stuff people think to put in them. Google Buzz will be just another node (a very good node, I hope) among many peers. Users of any two systems should be able to send updates back and forth, federate comments, share photos, send @replies, etc., without needing Google in the middle and without using a Google-specific protocol or format."

Google has most recently turned on WebFinger in Gmail (via RRW). WebFinger is described as being about making email addresses more valuable, by letting people attach metadata to them. According to the WebFinger page at Google Code, that can include things like:

- 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.

WebFinger is enabled for all Gmail/Google Profiles with public profiles. Google's Brad Fitzpatrick discusses more technical details about it here.