What features are people looking forward to in .Net 4.0 - 4.1

Question

I am very interested in learning what features people are interested in in the forthcoming .net framework(s)?

Whether these be new classes or new controls I am curio

Answer 1

I do a lot of work with Expression, so I'm looking forward to the extra expression types.

I also like optional/named arguments - but mainly as a way of making immutability simpler; not sure I'd use it much otherwise...