To the right of the "L" and "ON" LEDs, near the voltage regulator, are 2 rows of 4 holes, which look to be 2mm spacing. What are these for?
Vias to conduct heat away from the voltage regulator to the other side of the board.
I see, thanks. They almost looked like places to put on a header for something (I know xbee has 2mm pitch, but that's also a bit more than 8 pins 
), but there didn't appear to be any traces to or from them. A heatsink makes sense, though.