Windows Azure is Microsoft's cloud platform, and it give you great flexibility for developing, deploying, and managing applications. Many of Windows Azure's capabilities are not as well known as those of other Microsoft products, and Matt Hester gives a great overview of what Platform as a Service (PaaS), and Software as a Service (SaaS) mean. Matt also explains what these technologies can do for you and your business in his review, "What Is Windows Azure IaaS?". Check out this useful article at http://www.petri.co.il/what-is-windows-azure-iaas.htm.
Matt give some great clarification, including the idea that cloud computing doesn't have to be all or nothing. Matt concludes his article by stating:
"One aspect that makes IaaS great is the ability to leverage IaaS as part of overall architecture and offer the ability to extend your on-premise data centers. I know what you're thinking: Wait, I thought I had to put it all in the cloud or nothing. That is simply not the case. This is a common use of IaaS, which allows you to straddle the fence between on-premise datacenters and cloud services. You can have part of your application on-premise and the rest in the cloud. This is a common example of a Hybrid Infrastructure or Hybrid Cloud. IaaS allows you to have the best of both worlds for your infrastructure requirements and business demands. It provides native capabilities for you to quickly network these environments together. In IaaS you can leverage private networks for just your VMs or extend your own datacenter into the cloud so that the machines have full participation in your LAN and/or your extended datacenter resources."
For anyone interested in the cloud and Windows Azure, this article is a must-read.