I've spent a lot of time writing code to connect up user's contacts across different services, so I've had high hopes of WebFinger, the universal API to connect public profiles with email addresses. To be honest though I worried it might just be a geeky pipe dream that never gained widespread support from ISPs. I'm extremely happy to be proved wrong by Google's release of an implementation for all their public profiles.
To celebrate, I've added some PHP code to implement the protocol within FindByEmail, my attempt to combine all the email APIs into one package. The WebFinger code is actually fairly self-contained, so it should be easy to rip out and use in isolation. It is very early days for the protocol, and as far as I know only Google has implemented it, so I'll be keeping it updated as I learn more. To see if it works on your email address, give it a try for
Interestingly enough Google already had their Social Graph API that exposed a lot of the same information about public profiles, but it never really achieved widespread adoption. I'm really hoping WebFinger will become a much more widespread standard.