MakerBot Cupcake-compatible Pololu stepper driver board

I really wanted to move to a microstep-capable stepper driver, and heard lots of good things about the board from Pololu that is based on the Allegro A4983 (http://www.pololu.com/catalog/product/1202). I went through several iterations of my PCB, and here is the "final" version -- well, it's the one that I sent in for prototyping. Note that there isn't any silkscreening on this image because ExpressPCB's proto service doesn't include that or soldermask. I drew the text as traces so there would at least be some labeling. Those weird cutouts inside of the U1 footprint are there because I thought some people might want to try to install the Pololu carrier board underneath the PCB if they were hurting for space above the board. I do not yet know if the location is in a good spot for the capacitor, yet. The small hole in the lower right corner is for the pot adjustment, and the hole in the middle is for the Allegro chip. Makergear gives a screw to use as a heatsink, so I figure peopl