I was able to attend the CAB training session at Redmond earlier this week. It was a very informative couple of days. We were able to meet and talk with the dev team of CAB. We went through a series of Hands On Labs that will be available soon. I am still trying to get my head around the how CAB works at a detail level. I have a good understanding of things at at a higher level.
If you are building a larger client application (non ASP) then you would be doing yourself a favor by looking at it. It is an implementation of MVC or MVP (Model-View-Controller or Model-View-Presenter). One of the big advantages that I see in it is consistency. If some dev thinks it's a good ide to put a couple of hundred line of code in the click event of button, it will stick out like a sore thumb. Another great feature is the extensibility. You can your own Services (a service provides functionailty such as persistence or cryptography) or workspaces (a container for visual items). This allows a great deal of flexibility and also allows you to create a framework that can offer a high level of reuse.
As I get more comfortable with CAB I'll try and post more about it.