Python + Arduino with Mac OS X

The easiest way to communicate in Python with the Arduino (or any microcontroller with serial) is using pySerial.

Here's an example:

import serial
s = serial.Serial(port='/dev/tty.usbmodemfa141', baudrate=9600)

s.write('text')
s.read()
s.readline()

PS: If you're using Python 3, you should send bytes instead of strings (that is, b'text').