Microsoft announced that "Windows SteadyState will be phased out effective December 31, 2010. Microsoft will no longer support Windows SteadyState after June 30, 2011. After June 30, 2011, support will be limited to the resources that are listed under the Related Resources section, in this article," said Microsoft in KB2390706.
"Windows SteadyState helps you keep multiple computers in a school computer lab, an Internet café, a library, or even your home running the way you want them to, even when many people regularly use them. User privacy is also an issue for shared computer environments. Shared computers frequently use shared user accounts that make Internet history, saved documents, and cached web pages available to subsequent users."
Windows SteadyState was created to provide an effective way to help defend shared computers from changes by untrusted users and unwanted software installations—and help safeguard system resources.