Google has been generating a lot of cloud-based services news lately, but this one really shows some interesting business logic on their end. Google Message Continuity will provide a service that will permit offices to continue working with Microsoft Exchange even when their servers have gone down for the count—either due to an actual hard crash or a temporary maintenance cycle.

All Things D brings us the news about this expected service,

Google is jumping into that business with some additions to its Postini service for businesses that it will announce today. The new service will be called Google Message Continuity, and its being aimed squarely at users of Microsoft’s Exchange 2003 and 2007. Messages, contacts, folders, calendars and other aspects of the corporate email environment are replicated within GMail, constantly updated and synced so that in the event that the Exchange server crashes for a few hours or days or if it goes down for scheduled maintenance, users can have access to their messages, and keep getting things done from within GMail until it’s fixed.

One benefit for Google is that any business that uses this has an easier time dumping Microsoft Exchange altogether and moving to Google Apps: Once you’ve got your corporate email environment replicated on GMail, there’s no more worrying about the logistical headache associated with migrating from Exchange to Google Apps. Sneaky, right?

The search giant certainly has been all about data portability, but not just portability from themselves to others, they’d love to port data from others to themselves. Plus, if a business can trade Exchange for Gmail in the future when Gmail suits them better, it’ll make for an excellent move on Google’s part. Sneaky? Yes. Also brilliant.

Since it’s possible for Google to allow a near-seamless experience after the Exchange server crash, most of the office workers would probably not even notice much when it happened. In fact, done properly, Google’s takeover would just become the new source for the office Outlook to look to during the outage, possibly reducing some functionality, but keeping interconnection intact.

What company could go without backup generators for e-mail?

It looks like Google is offering the service to existing Postini customers for $13 per-user-per-year and $25 per-user-per-year for new customers. The service already boasts about 80,000 businesses and 21 million end-users.

The numbers are already strong and with this new capacity on the table that is certainly set to inflate.