First of all, the MPU9150's I2C default address is 0x68 which it turns out is the same as the very common DS1307 clock and every other RTC I've looked at. Please change the address to 0x69 or at least break out AD0 to a solder jumper on the bottom.
Secondly, I have found that many (all?) of the more advanced libraries for using data from the IMU rely on the INT pin being broken out to signify that the FIFO buffer is full.
See http://playground.arduino.cc/Main/MPU-6050 (Note that the MPU6050 is just a six axis version of the MPU9150 used by the OpenROV device.)
I can get the raw data, but it looks tricky to turn it into something useful.
Finally, it would be great if Jeff Rowberg or someone else, could add the MS5803 to the list of devices supported by his i2cdevlib project.