Currently the whole behavior framework and APIs only come with expression blend (and its SDK) but I noticed that a crucial part of it resides in the namespace System.Windows.Interactivity. Does this mean that in a future version of the .NET framework, maybe even 4.0, behaviors will be part of the .NET Framework itsleft and do not require the extra DLL that come with Blend (and its SDK)? Maybe some day I could even omit the xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity" in my XAML files? Does anyone have more info on this or knows where to get it?