Opening on behalf of Brandon Wallace: 

http://lists.w3.org/Archives/Public/public-pointer-events/2012OctDec/0003.html

Recommended details to add (based on IE10's implementation):

  1.  You can only capture a pointer if buttons>0 (e.g. mouse button is down, finger is on screen, or pen tip is on digitizer). So you can't just spy on interactions with UI outside your scope.
  2.  Once you set capture to a pointer, its target property will always be the capturing element. So while you can monitor movement of the pointer outside your contact (again, only while it's down), you can't get references to elements, etc.
  3.  Capture is automatically release when the pointer comes up (e.g. buttons==0).
  4.  Pointer events are not dispatched to elements not in the document.