Exciting news today!  The Unity Application Block was released by the patterns and practices team.  I just caught wind of the release.  If you are wondering what is Unity then let me try and explain.  From P&P - It is a lightweight, extensible Dependency Injection (Inversion of Control) container.  It facilitates building loosely coupled applications and provides developers with the following advantages:

• Simplified object creation, especially for hierarchical object structures and dependencies;
• Abstraction of requirements; this allows developers to specify dependencies at run time or in configuration and simplify management of crosscutting concerns;
• Increased flexibility by deferring component configuration to the container;
• Service location capability; this allows clients to store or cache the container.

Getting Started

For an introduction to dependency injection, see the article Inversion of Control Containers and the Dependency Injection pattern by Martin Fowler.
Two Quickstarts packaged with the release are also a good start.

System Requirements

The following are the minimum system requirements for Unity:

• Microsoft Windows XP Professional, Windows Server 2003, Windows Server 2008, or Windows Vista operating system
• Microsoft .NET Framework 2.0, 3.0, or 3.5
• Microsoft Visual Studio 2005 or Visual Studio 2008 development system

Resources

• MSDN site: http://msdn2.microsoft.com/en-us/library/cc468366.aspx
• Community Forum: http://codeplex.com/unity

Happy coding!