Yeah, I can't see VB9/C#3 generating any interesting comparisons. As with the previous version, they are effectively moving in lock-step this time.

I agree that the bigger deal is Vista. There are enough Vista-only features in .NET 3.0+ that we could easily end up writing extra code to detect whether our app is running under Vista or not, so the app can take advantage of the new OS or not based on that fact. It has been a long time since we've had to mess with that sort of thing, and it is a PITA - but I think we'll be living in a mixed XP-Vista world for quite a long time...

I try to stay at arm's length from the UI, so I can focus on the business layer. My UI support is through the established data binding interfaces (which are quite powerful), and a couple interfaces of my own design to fill in some gaps (such as authorization and exposing rule associations).

It should be quite realistic, with CSLA 2.1, to build reusable validation controls for ASP.NET that rely on the validation rules set up in your business objects. That was largely the motivation for exposing the rule definitions using the rule:// URI format.

For Windows Forms and WPF the need simply doesn't exist. The ErrorProvider in Windows Forms, and the ValidationPanel I'm building for WPF, work against the standard data binding interfaces for validation feedback and provide good separation between the UI and business layer automatically.