What Microsoft UI technology was used to create Zune Media player (marketplace software, not device os)?

Question

UI looks like it could me made with silverlight, but it's not a web app.

Answer 1

I thought it was WPF too at first, but it appears Microsoft used to a custom language called UIX (related to media center) to make it.

http://www.istartedsomething.com/20071116/microsoft-iris-uix-framework-zune/