A Tracking Protection List (TPL) contains web addresses (like msdn.com) that the browser will visit (or “call”) only if the consumer visits them directly by clicking on a link or typing their address.
Anyone or any organization can create a TPL (it is just a file that can be placed on a website) and consumers can add and remove lists as they see fit, having more than one if they wish. To keep everyone’s experience up to date, the browser will automatically check for updates to lists on a regular basis.
In go all the normal ad serving websites. And that seems like a pretty big shot across the bow of Adsense by Microsoft.