Here is a rough layout for the SharkFin.
1. The lower right hand corner is square. All components are aligned relative to this corner. The actual orientation will put the LEDs horizontal.
2. SparkFun and Pololu make the layouts for the three daughter boards available. It may save a lot of space and money to put those parts right on the motherboard. For know, routing can be done underneath of the daughter boards.
3. S1 is reset, S2 is for mode changing (night/day), S3 is power, and SEL is power select.
4. Note Power Down pin on Gyro is grounded. This stops spontaneous shutting down of the gyro.
5. I'm not sure if power select is required. I'm worried that I would be able to communicate through the USB at the 3.3V level provided by the power supply circiut.
6. The ATMega 328 is only rated at 12MHz for 3.3V. Not sure how this will impact serial connection. Might just fudge a little and try the 16MHz osc at 3.3V. Seems to work on the BEBL!
7. Routing may be tricky. Looks like a two sided board to me.
8. D5 is not an LED, but a Zener Diode as for programming feedback ala LadyAda's supped up boot loader.
9. The two large circles are through holes for mounting the board to the helmet.