A lot of the Xbox data is based on JSON or OData feeds. There are no official SDK/APIs to obtain this type of information, however you could easily find the feeds you require by using Fiddler and intercepting the requests from Xbox music on your device and subscribing to the same data. There is a guide to using Fiddler on Windows Phone here: www.fiddler2.com/phone/

There is obviously a significant risk of the feed changing, and impacting your app - so if you are going to do something like this I would advise proxying the data through your own service so you can rapidly make and deploy changes if something breaks.