Google announced support for the OAuth 2.0 protocol, although the standard isn't yet complete. Version 2.0 is designed for developer simplicity. Developers frequently complain about the difficulty of using OAuth to integrate applications with Google Apps.Today
Google also introduced a new OAuth consent page that it hopes will be simpler to understand.
Google announced support for OAuth back in 2008. Since then the standard has become widely used. The first version of the protocol standard was released in April 2010. Since that time it has been adopted by Facebook, among others.
Google's documentation for OAuth 2.0 can be found here.