Gen2 pointing device

[elw at stderr.org]

>> This could work:  http://en.wikipedia.org/wiki/Pointing_stick
>> It might be possible to mold it right into the keyboard, preventing
>> entry of liquids or grit while cutting costs.

I've been following the MAKE-and-friends articles / blog posts about 
homemade multitouch controllers with some interest;  folks have had good 
luck with things like a plastic bag filled with dye (with an iSight 
underneath...) and with something like a tablet sandwich (plexiglass, 
silicone coating on top, film under that, IR leds around the edges, and 
some sensors underneath...

$2 bag input here:

http://www.37signals.com/svn/posts/615-erling-ellingsens-2-multi-touch-pad

plexi multitouch table here:

http://tinker.it/now/2007/02/28/multitouch-table-experiment/

The latter, with a few more associated design innovations (like not 
needing to put a camera way down under the panel...), might make a dandy 
sort of input... it shouldn't care too much about dirt.  One would want to 
hook it to some sort of processing hardware that is able to detect state 
changes rather than just detecting "anything that isn't a non-active 
area"... you want to make it resistant to damage and wear, after all.

--elijah