Silverlight 4 is a major release that includes many new features such as support for additional browsers and platforms, improved networking capabilities including sockets support, enhanced data binding and validation, improved media support including offline DRM, and new controls. It also introduces the ability to create trusted out-of-browser applications that have increased desktop integration and access to native capabilities. The release strengthens support for MVVM, adds the Managed Extensibility Framework, and improves WCF RIA Services.