Robert Scoble interviewed Peter Loforte, general manager of the Tablet PC team, and asked him to show off some of the new features of Windows XP Tablet PC Edition 2005. The interview is posted on Channel 9.
Context based inking is very cool. I did not know the level of context involved until I watched the video. Entering a state name in the United States? The recognizer will try to match your scribble to one of 50 options. Entering a URL? The recognizer was trained on top site URLs from around the world, and also checks your history for a possible close match.