Ed Brill has a piece discussing Microsoft's recent boast that it expects a very large number of it's current Exchange base to shift to a hosted Exchange service. Ed's rightfully taking issue with the fact that Microsoft seems so incredibly sure that they'll be welcoming throngs of disaffected IBM Lotus Domino users to the service. While he seems to almost dismiss cloud-based enterprise services, both Microsoft and IBM would be wise to eye Google's enterprise apps. If I were running a rather large enterprise right now...or even a smaller one, I'm about 99.9% certain that I would be paying $50/user to Google right now for Google apps in the cloud. Not only would we be getting a world-class browser-based email experience with POP and IMAP support but we'd be getting 24/7 support, super security and compliance via postini that includes archiving, encryption, content policy management, robust spam prevention, private versions of all of Google's apps, a robust standards-based calendaring service and much, much more.
Google Apps for the enterprise.
Google Enterprise App security