What are Lambda Expressions?

English:
Lambda expressions, new in Visual Basic 2008, are a handy addition to any programmer's toolbox. They are callable entities that are defined within a function, and they're first-class citizens; you can return a lambda expression from a function and you can pass lambda expressions to other functions. Lambda expressions were added to Visual Basic 2008, formerly code-named "Orcas," in order to support Language Integrated Queries (LINQ), which adds data programmability to Visual Basic (more on that later). As you use lambda expressions, you will begin to see the power and flexibility they promote. I invite you to sample the basic concepts of lambda expressions, explore their benefits, and witness how to use them to write more expressive programs.

http://msdn.microsoft.com/msdnmag/issues/07/09/BasicInstincts/default.aspx?loc=en

繁體中文:
Lambda 運算式是 Visual Basic 2008 的新增功能，也是所有程式設計師的工具箱不可或缺的利器。它們是定義在函式內的可呼叫實體，且是第一等公民；您可以從函式傳回 Lambda 運算式，也可以將 Lambda 運算式傳遞給其他的函式。Lambda 運算式是 Visual Basic 2008 (原來的名稱代碼為 "Orcas") 新增的部分，為的是要支援 Language Integrated Queries (LINQ)，這可以提升 Visual Basic 的資料可程式性 (將於稍後詳述)。隨著您使用 Lambda 運算式，您將會了解到它們的威力與彈性。我竭誠邀請您來體驗 Lambda 運算式的基本概念、探索其優勢，以及目睹如何運用它們來撰寫更具表達力的程式。

http://msdn.microsoft.com/msdnmag/issues/07/09/BasicInstincts/default.aspx?loc=zx