Is this a joke?.NET Framework is a framework, why on earth would it be versioned by it is compiler or runtime version?Marketing and reality might join again , if the .NET Framework 4.0 will incorporate the Dynamic Language Runtime (DLR).???The Dynamic Language Runtime (DLR) is a layer on top of the .NET Framework 3.5 aiming at help you to build dynamic languages in .NET.Source: www.dotnetguru