The OS system is integrated with your Google Account.  

At the moment, the extent of the integration with your Google account consists of the following:

• Login: Once you are logged into your Google account, you are automatically logged into the OS*
• Gmail: Send an email from your Google email account directly from the OS (More of Email)
• Calendar: View your calendars and appointments from within OS.  Appointments created from OS will automatically be pushed to your Google Calendar.

Soon to come: Google Contacts, Google Talk, Google Drive, and more!

* Yubikey second factor authentication can also be required for some users