http://rosettacode.org/wiki/Color_of_a_screen_pixel

get_pixel.py

def get_pixel_colour(i_x, i_y):
	import PIL.Image # python-imaging
	import PIL.ImageStat # python-imaging
	import Xlib.display # python-xlib
	o_x_root = Xlib.display.Display().screen().root
	o_x_image = o_x_root.get_image(i_x, i_y, 1, 1, Xlib.X.ZPixmap, 0xffffffff)
	o_pil_image_rgb = PIL.Image.fromstring("RGB", (1, 1), o_x_image.data, "raw", "BGRX")
	lf_colour = PIL.ImageStat.Stat(o_pil_image_rgb).mean
	return tuple(map(int, lf_colour))
 
print get_pixel_colour(0, 0)