This quick little program demonstrates how to call the send_notification.sh script with a program variable to display whatever notification message you prefer. This can of course be in response to any logical condition you would like to track in your Python program.
There appears to be a limit to the length of the message - more than 40 characters and you will get an "Unknown Error" upon receiving the notification, but it will still be sent.
from subprocess import call
name = raw_input('What is your name?\n')
print 'Hi, %s.' % name
call(["send_notification.sh", "1", name, "ok"])
This was tested on a Raspberry Pi with the Raspbian "Wheezy" image installed.