I just found an article that is very interesting. It goes into some fairly detailed examples of the X-GOOGLE-TOKEN and how Google distributes these tokens securely over SSL.
According to the article, Google is creating an easy-to-deploy authentication structure without the licensing fees that prevent Microsoft Passport from becoming more widely used. This is mechanism is known as Gaia Authentication.
Google hands out tokens securely over SSL. You can use those tokens to auth yourself on XMPP. You can authenticate yourself with your one single Google Account without ever having to give a third party your password. -- dystopics
Once this is opened to the public, it could be a huge step in the right direction for Google. If Gaia is simple to implement and becomes widely used and accepted, people and companies will grow even more dependant on Google.