dotnet framework 4.0

Application Compatibility and Deployment > Related to deployment.

                  Client Profile

                  In-Process Side-by-Side Execution

                  Portable Class Library

Core New Features and Improvements (with the .NET Framework 4, you can get processor usage and 

memory usage estimates per application domain), 

Background GC, 

dotnet framework 3.5

3.5 > LINQ, AJAX

dotnet framework 3.0

3.0 > WCF, WPF, WWF

dotnet framework 2.0

2.0 > Generics, Partial classes, anonymous methods, nullable types