For those that missed it (like me), the Windows Vista User Experience Guidelines has been updated with some additional content. This update add content in the following areas:
These guidelines are crucial to ensure the most consistent user experience possible. Though many don’t, this is a document that all developers should read. I firmly believe that consistency is the most important single factor in design, and following an established style such as this is a great way to ensure that a UI is as consistent as possible.
If you’d like some background reading, the XP version is still available.