Google Apps is being rolled out to countless users and organizations each day.
For many various reasons, Single Sign On (SSO) access to Google Apps is desired by those organizations. Google requires compliance with the SAML 2.0 security protocol in order to provide support for Single Sign On into Google Apps.
From the user perspective, they do not want an awkward, intrusive, difficult, or time-consuming experience. In short, they want to be able to operate and act as they always have done in the past.
Innovative IT organizations have recognized that these users are accustomed to (and widely accept) the notion that they need to sign in to the desktop machine each day, providing an ID and a Password.
These innovative IT organizations have embraced the optional deployment model of leveraging the ID and Password that the user provides when logging in to his desktop each morning, as the mechanism for triggering SAML 2.0 based Single Sign On (SSO) to Google Apps.