There are many, but I will suggest that the more exciting things coming are the maturing technologies that I use. Project Astoria which changed to ADO.NET dataservices and then has had two CTP releases out of band will finally be brought into step with .NET 4.0 and be called WCF dataservices.
A restful data access layer with language integrated query and the power of anonymous and instance methods and type inference means you can write things like this semi psuedo code, with a lot of the problems ironed out and a lot of good forum knowledge:
Button.Click += new EventHandler((o,e) =>{DG.ItemsSource DataContext.tblUsers.Where(f=>f.active ==true;);
Don't mention MVVM or inefficiencies etc, but I believe this code does on one line what would take a fair few to do in .NET 2.0