http://www.youtube.com/watch?v=kownnnxs7eI There has been a pen input method since Vista at least.
As you can imagine, I jotted all of this down as a first-impressions stream of consciousness.
As a pen-input newbie, I wasn't even aware the virtual keyboard had a pen mode. That's close to what I had in mind. I still find it bizarre that it's not more integrated with Onenote.