Microsoft Active Accessibility is a COM-based technology that provides a standard, consistent mechanism for applications and Active Accessibility clients to exchange information. Additionally, it provides lightweight UI test automation. For more information refer to the following articles:
MSAA it is also a great automation tool, which Microsoft included in Visual Studio 2010. The automation allows developers to access and manipulate all UI elements in applications that support it. However, at this point only the standard Windows Forms controls have support for this technology, and it is quite limited.
Telerik UI for for WinForms allows you to create a simple coded UI test using MSAA in a few mouse clicks. An example is available here.