We have implemented single sign-on across most of our sites. The setup is straightforward, in that it uses the Google Apps Login plugin.
For sites which are only logged into by staff, it will completely bypass the wordpress login page and take you directly to the Google sign-in page
For sites where users also have a sign-in, we don’t want them trying to use the google login since, for security, it is deliberately set to only work with @bitesizebio.com email addresses and will otherwise display an error. We took the opportunity to apply some light branding to the login page, to make it more visually appealing than the standard wordpress login.
Therefore we have added a function to functions.php which hides the login button and adds a deliberately subtle ‘staff login’ link at the bottom, which serves the same purpose.
The only note of caution is that the process has to be tied to an active Google acount. Currenly this is fraser@bitesizebio.com.