Well im sure you can check this sites archives to find the original story on the patent and obviously there hasn't been a product with it implemented (made by apple), and also obviously the list of patents apple has licensed is not public. However just seeing the macrumors take on makes it clear that the touch cover uses this technology.
I can't find anything to show it wasn't licensed. This is something you are 100% sure of.
Seeing as Microsoft have licensed other Apple patents I can't see how you are 100% positive they have infringed any patent.
Can you show how you have reached this degree of certainty?