Yes, you can login to your Google Apps mail using your OpenID from myOpenID.com. To do so, follow these easy steps:
- Log in to your Google Apps Admin Console.
- Go to the "Security" tab and click on the "Advanced Settings" link.
- Scroll down to the "Authentication" section and select the "OpenID consumer" option.
- Enter the URL for your myopenID account in the “OpenID providers” section and click “Save Changes”.
- Now, whenever you want to log in to your Google Apps mail, you will be prompted to enter your OpenID URL from myOpenID.com.
For more information on setting up OpenID with Google Apps, please refer to this Google guide: https://support.google.com/a/answer/158587?hl=en