Microsoft will be the first to provide a comprehensive "Private" Platform as a Service (PaaS) offering based on the current Windows Azure Platform, called the "Windows Azure Platform Appliance". If you know anything about Windows Azure, just take all the inovation, efficiency, scalability, elasticity, automation, self-healing/self-managing, and multi-tenancy... package it up in a box and run it from within your own data center. Dell, eBay, HP, and Fujitsu all intend to deploy this appliance as a vehicle to expanding their cloud services. In fact, just recently Fujitsu announced they are going live with global cloud services using the Windows Azure Platform Appliance.
So what's the good and bad of this Private PaaS appliance? The bad thing is no doubt going to be the "capital expense". Most businesses are looking for ways to cut cost and get out of the IT business where it makes sense. Eliminating the hardware cost is one primary benefit of going to Windows Azure, among many others obviously. Without exhausting this blog with all the benefit of Azure itself (which this appliance inherits), the true benefit of the Windows Azure Platform Appliance is "control". For some industries (healthcare, financial, government, etc.) the benefit of having this appliance behind their firewall may out weigh the capital expense of the appliance itself.
When should we expect to see these appliances for sale to the consumer market? There hasn't been any official date, but one could reasonably suspect to see something ship in calendar year 2012.