Microsoft has released the May 2008 version 4 of the Microsoft Patterns & Practices Enterprise Library. Microsoft describes the Enterprise Library as:
Enterprise Library consists of a collection of application blocks and a set of core features such as object generation and configuration mechanisms. All of these are reusable software components designed to assist developers with common enterprise development challenges. Application blocks help address the common problems that developers face from one project to the next. Their design encapsulates the Microsoft recommended best practices for .NET applications; developers can add them to .NET applications quickly and easily.
The new release is described as:
This release of Enterprise Library includes a new application block (see The Unity Application Block). Unity is a lightweight, extensible dependency injection container with support for constructor, property, and method call injection. You can use the Unity Application Block as a stand-alone dependency injection mechanism without requiring installation of Enterprise Library. However, this release of Enterprise Library incorporates integration with Unity that provides new opportunities for generating instances of Enterprise Library objects. There are also additions in functionality to several of the existing application blocks. The following sections discuss these and other changes in the current release. In addition, this release has been adapted to work with Microsoft Visual Studio 2008, Windows Management Instrumentation (WMI) version 2.0, and the Microsoft .NET Framework 3.5.