It was a bit more complex than that, but I can't find the billion number.

http://online.wsj.com/news/articles/SB1000142405270230391690...

In any case, they settled for a negative value a lawsuit alleging B&N violated Microsoft patents. If that doesn't send a message about what those patents are, I can't imagine what would.

Not sure why the other comment was killed, but it seemed to list them: http://www.geekwire.com/2012/microsoft-barnes-noble/

This list is not a complete one