Hi Xi and Peter,
It turns out that there was no continuity between the SCL and SDA pins and the IMU chip pins. I isolated the error to the length of trace between the lower breakout holes and the upper break-out holes. The discontinuity could be caused by my thumb-handed buffoonery while soldering, or there may be a common-cause failure of both traces on the PCB.
I was able to fix it by soldering wires to connect the lower to the upper breakout holes. If you want to salvage your BerryGPS-IMU, you could see if that is the problem and give it a try!