Downloaded the beta of Visual Studio 2010 today. I was expecting WPF to have worked its way in deeper than it has done, currently its only in the editor, but the changes are very nice. Oddly enough I espcially like the text selection effect, as well as the scaling and general look and feel. In addition the changes of Intellisense now filtering is very nice.
Havent had much chance to try out the .NET 4.0 additions, I am quite looking forward to playing around with the new dynamic types. One change that caught my eye on the Web Forms was the ClientID addition, with the added ability to control the client id of server controls directly it'll bypass the need to "tell" javascript what server control IDs are.
Will post again once I've had some more time with the new changes.