Detect movement in a very power efficient way
Your assumption about the MMA7660FC is correct. It can generate an interrupt for your controller in its "Active Mode". In this configuration the device draws 47 μA.
A better solution would be using this 3-axis accelerometer from ST LIS3DH. It does exactly the same thing, but using 2 μA instead.


I would say this is the most low-power solution for what you are describing. Hope it helps you.