The WM Team could learn something from UIQ HWR, the best I've ever used. It doesn't steal any screen area for the SIP, and has an excelent accuracy(as fast as writting on paper in my case). They divided the screen in 2 main areas and a horizontal middle
line, in the top you write the symbols and numbers, on the bottom all letters, and in the center line( indicated only by a small arrow tip on the right ) every letter is recognized as uppercase. By doing so the HWR has a reduced scope of posibilities, like
they did with Vista Voice Recog. limit the number of possibilities to improve accuracy.
I know WM has something similar(Letter Recognizer), but it takes up some screen space and isn't as accurate. Also, it is possible UIQ's solution is patented.