Software As A Service combines cloud back end services with either web based applications, or synced desktop applications..
What does this mean? It means that Microsoft should be looking over their shoulder in case another company decides it would like to get into the enterprise market. Google has launched their Google Apps SAAS offering which can act as a full exchange solution, with the ability to even migrate an existing exchange environment. Users can even use outlook with all the facilities of Microsoft Exchange without needing the server, or the air conditioned room the server lives in, or the backup infrastructure, or indeed the staff of computer experts to run it all.
It only requires an outlook plugin to work, which unfortunately does not work directly on the Mac. However the Mac can utilise sync tools to talk to Google mail/calendar/addressbook. The iPhone is able to sync with Google mail/calendaring/addressbook directly ironically using Google's licenced Microsoft Exchange solution. This allows Macs and PC's, plus many makes of mobile to use the same exchange like services millions of pounds cheaper than the Microsoft solution.
This is cloud computing at work. Microsoft still has the advantage of an excellent back end solution for PIM functions, many systems including the iPhone and Evolution Mail for Linux can directly sync with Microsoft exchange using a simple direct connection (unfortunately Evolution is not yet compatible with exchange 2007).
The complexity of running your own exchange environment is taken away by using Microsoft's cloud services. I think that Microsoft will move more and more into cloud backend services, and play less of a role in the front end of computer users lives in the future. However, Google has cloud services that work across a larger range of computer platforms and at a much cheaper price than Microsoft's cloud services.
Following the trend through to it's ultimate conclusion, it's clear that the traditional server room will cease to exist, being replaced by just a few massive data centres running hosted cloud services.
