#!/usr/bin/env python

import boto.ec2

conn = boto.ec2.connect_to_region('us-west-1', aws_access_key_id=YOUR_KEY, aws_secret_access_key=YOUR_SECRET_KEY)

script = '''#!/bin/bash

apt-get update
apt-get install git-core
# clone, whatever
'''

print conn.run_instances(
    image_id            = 'ami-19bfef5c',
    key_name            = 'dev',
    security_groups     = ['dev', 'dev-mattb'],
    user_data           = script,
    instance_type       = 'm1.small',
)