This is a good place to learn about wireless communications using an XBee and an Arduino. There are a lot of different sensors that could use this same code with only slight variations.
I managed to put together a wireless accelerometer the other night using my two new XBees, an Arduino XBee shield, an XBee Explorer USB, an ADXL330, and some Python. I struggled a bit with some of it, so here’s what I learned.
More about XBee & Arduino wireless accelerometer
In the Maker Shed: Arduino Mini Board, fully assembled