Android Interfaced X-Y Plotter

A comment on our recent post about an X-Y plotter led us to this fantastic creation.  Eason Ke has built what he calls an NXT Painter.  What makes this stand out above other X-Y Plotters is tethered to an android smart phone.  He's using what looks like a custom App on the smartphone to 'write' a word and then the robot replicates it perfectly on paper.

Eason, any chance of some more details on how it works?

**UPDATE**
Direct from Eason, here is more detail

I am rebuilding it and trying to post everything about it on my blog. There are three posts about it:
Model: http://blog.easonke.com/nxt_painter_model/
Demo code without Android, which draws a square: http://blog.easonke.com/nxt_painter_demo_code/
Some math behind demo code: http://blog.easonke.com/nxt_painter_code_model/
I will continue to post android part. Lejos is used. The android application collects touch events like up/down/moveTo(10,10) and sends them to NXT thru BT. NXT just follows all events.