One of the new features in WPF 4.5 is support for binding to static properties. In addition to the binding syntax itself, there’s new support for static property change notification.
In many cases, it is still advisable to use a Singleton pattern or another approach for binding. However, there are cases when your application design requires binding to static properties. In those cases, WPF should kindly step out of the way and let you accomplish your task the way you’ve architected it.
Read WPF 4.5: Binding and change notification for static properties from Pete Brown