The new sign-in page that was announced last November will be rolling out over the next four weeks starting today. With this change, the sign-in page for all Google Apps customers will be updated to be consistent across all Google Apps services. In other words, the sign-in page for Gmail will now be identical to the sign-in page for Google Calendar, Google Drive, or any other Google Apps service. This change will improve security and make it easier for users to switch between accounts. This means a few things for your organization:
The Google Apps sign-in page can no longer be personalized with colors and custom logos. It will now look the same across all Google sign-in pages.
Users will have to log in with their full email address (example: email@example.com)
For SSO domains with a network mask, users will be presented with the new Google sign-in page when they log in from outside the SSO network mask. This change does not affect SSO domains without a network mask.
Google Apps for Business, Education, and Government
For more information:
Reference by : http://www.google.com/