The company mailed the previous beta testers:
Thank you so much for being a part of the Microsoft Security Essentials v2 Beta. You have indicated that you are interested in receiving invites for Connect programs from Microsoft, so we would like to invite you to participate in the Microsoft Security Essentials Public Beta program on Microsoft Connect. This program is for the newest Beta version of Microsoft Security Essentials which has the latest protection features. Be one of the select few who get access to this Beta release by signing up now to reserve your spot!
The company has not revealed anything about the future editions of MSE though we believe that the newer version would feature more capabilities.
Microsoft has already hinted that Windows 8 would feature a more robust security solution which might be based on Security Essentials itself.