Code Contracts provide a language-agnostic way to express coding assumptions in .NET programs. The contracts take the form of pre-conditions, post-conditions, and object invariants. Contracts act as checked documentation of your external and internal APIs.
Doloto analyzes Ajax app workloads and performs code splitting of large Web apps so they can transfer initially only the part of the client-size JavaScript code needed for application initialization...
"Rx is a superset of the standard LINQ sequence operators that exposes asynchronous and event-based computations as push-based, observable collections via the new .NET 4.0 interfaces IObservable and IObserver. These are the mathematical dual of the familiar IEnumerable and IEnumerator interfaces for pull-based, enumerable collections in the .NET framework. "