Question about Sure Accelerometer DC-SS009

Hi,
Does someone has used the Sure accelerometer DC-SS009?
It is a 3 Axis Acceleration Sensor Board wich mainchip is the MMA7260Q from Freescale.
I am trying to use it with an Arduino but I am not understand the values I get in the A/D. For an axis (Y for example) the A/D read values ranging ~300 to ~400 ???. For example, if I stand the board at 0 degree I get 370. When I tilt it to 10 degrees, I get 380. When I return to 0 degree it read 370 again. No matter if I move it fast or slow. Would't it read acceleration? Is it integrating? What am I measuring?

Another strange issue is that sometimes the range changes to ~500 to ~800 when I turn it off and on.

I am using the device in the same place in my worktable. The values above are approximated.

Thank in advance.