Small Wireless Gyroscope & Accelerometer
There is no need for WiFi or Bluetooth or even a microcontroller.  All that adds to your size and power consumption.

The output of a 6 axis sensor is a serial bit stream.  E.g. The Invensense MPU6000 is about 4 x 4mm and takes about 1mA.

You will need to drive and configure the device, so a small FPGA, e.g. An Actel Igloo FPGA is also about 5x5mm and takes less than 1mA could be used.  It might be possible with some 6 axis sensors to use pin strapping or device defaults so driving and configuration ( and hence the FPGA) might not be required.

The output of the FPGA is passed to the input of the RF transmitter. Depending on the required sample rate (hence data rate)  You could use a descrete chip like this MRF24J40 or a module like This for the RF transmitter.

If you keep the data rates down you could probably run for many hours on a very small battery assuming the transmit distance is not too far.

You would then use a microprocessor board, e.g. The Arduino or Rasberry PI with a matching RF receiver device to pass your data to a computer or tablet over USB, Ethernet or WiFi.