The patterns and practices team has just released a new Composite UI Application Block.  Below is a short summary, or you can get more information here.

The Composite UI Application Block December 2005 Release is a source code-based component built on the Microsoft .NET Framework 2.0 that provides proven practices to build complex smart client user interfaces. It is based on proven design patterns in which rich and complex UI solutions can be built out of simpler user interface parts that can be independently developed, tested, versioned and deployed. It provides guidance on the architecture of your solution leveraging platform features of .NET including Windows Forms and ClickOnce.

Provided in Visual Basic and C#,  the Composite UI Application Block feature set is the result of extensive collaboration between our team and Customers, Microsoft Product Teams, Architecture Strategy, Platform Strategy, Microsoft Partners, Microsoft Field Organizations and the broad developer community. We thank all those who have participated in the process