CNET/ News.com has a great article on a street artist named Emil using a Motion Tablet PC as his digital sketchpad complete with pictures here:
http://news.com.com/2300-1041_3-5818755-1.html
With its bars and cinemas, London's Leicester Square is a popular destination for tourists, who'll often stop to have portraits and caricatures drawn. On one summer day, the artist Emil (in the white shirt) swaps his notebook and charcoal for a tablet PC.
Here is one of the pictures: