Microsoft Enterprise Library is a collection of application blocks designed to assist developers with common enterprise development challenges. Application blocks are a type of guidance, provided as source code that can be used "as is," extended, or modified by developers for use in enterprise development projects.
Enterprise Library consists of reusable software components that are designed to assist developers with common enterprise development challenges. It includes a collection of functional application blocks addressing specific cross-cutting concerns such as data access, logging, or validation; and wiring blocks, Unity and the Interception/Policy Injection Application Block, designed to help implement more loosely coupled testable, and maintainable software systems.
Different applications have different requirements, and you will find that not every application block is useful in every application that you build. Before using an application block, you should have a good understanding of your application requirements and of the scenarios that the application block is designed to address. Note that this release of the Enterprise Library includes a selective installer that allows you to choose which of the blocks you wish to install.
Microsoft Enterprise Library 5.0 contains the following application blocks:
Enterprise Library also includes a set of core functions, including configuration and instrumentation, and object lifecycle management. These functions are used by all other application blocks.
Check-out the April 2010 Release at: http://msdn.microsoft.com/en-us/library/ff632023.aspx