Drawing with the magic trackpad (OS X)

I've experimented with a Griffin iPad stylus and the Apple Magic Trackpad a few times, but found it awkward to click and draw at the same time in SketchBook Express, Photoshop or Illustrator, but searching around I found a few clues towards the answer.

First turn on three-finger dragging in System Preferences ... -> Trackpad -> Point and Click

Drawn in Illustrator (CS 3) and painted in Photoshop (CS3) using Magic Trackpad.
Time taken: about 1 min.

Now place the trackpad in the middle of your desk and gently place two fingers on your trackpad and then begin drawing with the stylus.

Lift off your two fingers to stop drawing.

Point at a tool with the stylus and add your two fingers back to select.

If you are making a brushstroke and lift the stylus off your trackpad instead of your two fingers, then the stroke will, in Photoshop and other programs, continue to glide on until your lift your two fingers. This is a nice free-flowing side-effect that I rather like.

(If you don't own a stylus you can draw and paint with three fingers instead.)

Note: I've tested the stylus on an aluminium MacBook (late-2008) with multitouch trackpad as well and the results are the same. It works. Both times I was using OS X Lion.