Very basic script that rotates a stepper motor with a Raspberry Pi.

stepper.py

#!/usr/bin/env python

# Thanks to http://www.youtube.com/watch?v=Dc16mKFA7Fo

import time
import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BOARD)

ControlPin = [18,22,24,26]

for pin in ControlPin:
  GPIO.setup(pin,GPIO.OUT)
  GPIO.output(pin, 0)


seq = [ [1,0,0,0],
        [1,1,0,0],
        [0,1,0,0],
        [0,1,1,0],
        [0,0,1,0],
        [0,0,1,1],
        [0,0,0,1],
        [1,0,0,1] ]

for i in range(256):
  for halfstep in range(8):
    for pin in range(4):
      GPIO.output(ControlPin[pin], seq[halfstep][pin])
    time.sleep(0.01)

time.sleep(2)

for i in range(256):
  for halfstep in reversed(range(8)):
    for pin in range(4):
      GPIO.output(ControlPin[pin], seq[halfstep][pin])
    time.sleep(0.001)