After spending many months fighting the Visual Studio 2005 XAML editor it is nice to work in VS 2008
There are lots of little extras in Visual Studio 2008. Here is a nice improvement in the XAML editor. When adding an xmlns attribute (mapping) there is a dropdown showing your project and all the .NET assemblies. Picking an item from the list will stub in the correct XAML. Once you have the namespace mapped you get Intellisense when using the tag.