Confirmed features of .NET 4.0?

Question

Does anyone know what will be in .NET 4.0?

I found tuples on codeplex:

....
// NOTE : this is a TEMPORARY and a very minimalistic implementation of Tuple'2, 
// as defined in http://devdiv/sites/docs/NetFX4/CLR/Specs/Base Class Libraries/Tuple Spec.docx
// We will remove this after we move to v4 and Tuple is actually in there
public struct Tuple<TFirst, TSecond>
....

Answer 1

Parallel Extensions

WCF/WF improvements

I expect BigInteger will be back, too. I'd really like to see a bunch of the F# immutable collections become part of ".NET proper" too - and that wouldn't surprise me at all.

Answer 2

Glenn Block confirmed on a recent Herding Code episode that MEF would be part of .NET 4.0.