Below is what I am working from. I followed the directions to try it before it was automatically installed to protect my site from possible disruption.
In about 4 weeks, your organization will receive an upgrade to your Office 365 service. You can experience the service upgrade with a small group of users immediately.
Here's what to expect:
• The service upgrade is automatic. There is nothing either you or your users need to do to receive the service upgrade.
• The service upgrade is automatic. There is nothing you need to do to receive the service upgrade.
Get excited
The Office 365 service upgrade provides great new features, including broader support for mobile phones and tablets, a unified user experience in the browser, social networking, and more.
Sincerely,
The Microsoft Office 365 Team
P.S. Not a good time? If you really need to, you can postpone the service upgrade right from the Admin page. Just do it before 22 January 2013.
Can't wait?
TRY IT NOW: select a small group of users to get the service upgrade immediately.
Visit the Office 365 Service Upgrade Center
You’ll find details about what’s coming, videos and feature walkthroughs, and templates for notifying users.