I recently downloaded the previews of the tools in Microsoft® Expression® :
http://www.microsoft.com/products/expression/en/default.mspx
While I've only spent a couple of minutes with the two products (Interactive Designer and Web Designer) I have to say I'm pretty impressed. Get ready for a HUGE learning curve to get up to speed with how interfaces will work in Vista (and here I haven't even got up to speed with the 2.0 version of the Framework! :( ).
I'm sure I'll be posting more about this as I explore it, so stay tuned! :)