Google has recently added three important enhancements to our OAuth support:
  1. The ability to use OAuth without registration
  2. Support for software apps installed on a computer or mobile phone
  3. Additional controls for our Google Apps Premier and Education customers which allows administrators to give another web application access to a subset of the data Google stores for that organization
Below is an overview of each enhancement, or you can refer to our updated OAuth documentation.

1. The ability to use OAuth without registration

Based on consistent feedback from our developers, we added the ability to use OAuth without having to register the website ahead of time. This change is especially helpful for developers working on test servers that cannot be accessed directly from the Internet.

2. Support for software apps installed on a computer or mobile phone

Many of the larger enterprises that use the Google Apps service choose to run their own login system. They accomplish this by leveraging our support for the SAML protocol which defines a way for Google to redirect the user to the company's login system to be authenticated before accessing their mailbox at Google.  However, in this situation Google normally does not have a password for the user — especially if the enterprise authenticates the user with a password and with a second factor of authentication (such as a token generator they carry on a keychain). Unfortunately, there are many installed software applications created by both Google and ISV developers that use Google's APIs, and those applications are hardcoded to ask a user for their email and password using Google's ClientLogin API. With this new OAuth feature, the software application can now launch a web browser and start a process that both logs the user in through their central SAML login system, and that also gets the user's consent to access their data hosted at Google. Because the user authentication is done in the web browser, it will work with the enterprise's existing login system.  Google is encouraging any ISV that uses the ClientLogin API to add support for this new OAuth flow, enabling usage by the large enterprise customers described above. Google is also planning to enhance our Google Apps Sync for Microsoft Outlook to support this feature such that Outlook can be used with both Google Apps and an enterprise's central login system.

3. Additional controls for our Google Apps Premier and Education customers which allows administrators to give another web application access to a subset of the data Google stores for that organization

This feature for our Google Apps Premier customers enhances our existing OAuth for Google Apps domain administrators, also known as 2-legged OAuth. This feature enables domain administrators to allow specific IT apps or third party web services limited access to user accounts via a centralized permissions system under the control of the  domain administrator. For example, with this new system, an administrator can use the Google Documents API to configure every user in the domain to have a Google Docs folder named "Human Resources" that is automatically populated with common employee forms.  The company might also sign up with an Enterprise SaaS vendor such as Manymoon and specify that Manymoon can access the Google Calendars of all of their users, providing tighter integration with Manymoon's project scheduling features. Previously, this feature required giving the third party vendor access to all of the data that Google stored for that organization, but with this new feature, administrators can limit access to particular data sources (Calendar, Documents, etc). Refer to our documentation for more information.