Those who participated in the beta received the following email:
Dear Beta User,
Thank you for joining the Microsoft® Security Essentials Beta. We hope you have enjoyed using the Security Essentials Beta and found it easy to install and use.
The final release of the latest version of Microsoft Security Essentials has recently been released and the beta program will end on April 26th 2012.
During the next days, participants who installed the Security Essentials Beta and are subscribed to automatic updates will be upgraded to the final release of the latest version of Microsoft Security Essentials after they agree to a new license agreement. If you would like to upgrade manually, please visit http://www.microsoft.com/security_essentials and click on the “Download Now” button. There is no need to uninstall before upgrading.For more information about automatic updates through Microsoft Update, please visit http://www.microsoft.com/windows/downloads/windowsupdate/automaticupdate.mspx.
Please note that in order to continue receiving technical support, you will need to upgrade or install the final version of Microsoft Security Essentials.
Thanks again for participating in the Microsoft Security Essentials Beta.
The Microsoft Security Essentials Team