A lot of Google/GMail news in recent days: first the Priority Inbox update and now Message Continuity. It’s a corporate cloud service for companies which want to have a backup when their Microsoft Exchange goes down. The new service is powered by Postini as noted on the official Google Blog: Google acquired Postini back in 2007.
The way Message Continuity works is by replicating email accounts which are hosted on Microsoft Exchange servers using the cloud services of GMail, Contacts and Calendar. In the event of failure, maintenance or (scheduled) downtime logging into GMail will suffice to continue email communications.
Next to having a backup in the cloud, actually making the transition to Google Apps later in time will be easier for companies because the data is in sync between both platforms: there will be no need to migrate email, contact and calendar data.
More information can be found on the Google Enterprise Blog and at www.google.com/postini.