The python script checks if Linux i2c-tools have been installed and in that case it runs a loop that gathers and publishes altitute samples. The sensor can also get samples of pressure and/or temperature. Take a look at the datasheet for more details.
There’s also more information about the sensor at the Data Manipulation and Basic Settings of the MPL3115A2 Command Line Interface Driver Code and Sensor I2C Setup and FAQ. The equations used for the altimeter are further explained at Pressure Altimetry using the MPL3115A2.
In order to test the package with the Bone, this breakout board has been used.
Although some people have found some issues with it, the communication seems fine however the values that the sensor output are about 100 meters below what i was expecting.