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

Mostly parallel extensions and 'variance. And of course: System.Reactive / the Rx Framework / "LINQ to Events", which I think could be(come) very big.

But there are other things I have not seen mentioned here that - while "just nice to have" in a way - might come in handy when the new version is finally there. Like:

• BigInteger (to bad something like a INumber didn't make it in yet...)
• ISet and SortedSet (self-balancing trees in the Framework)
• Changing file system enumeration APIs from returning arrays (only?) to returning IEnumerable (as well?)
• Default support for F# language
• Slight compression improvements

I think dynamic and optional/named parameters are just there to enable better/easier interop with languages that use/need/require these concepts. So they are nice to have available. But surely nothing more than that.