A simple script to update the AWS Route53 entry using "boto".

ddns.py

#!/usr/bin/python

import boto
import boto.route53.record

access_key = 'XXXXXXXXXXXXXXXXXXXX'
secret_access_key = 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
zone_id = 'XXXXXXXXXXXXXX'
domain = 'example.com.'   # last '.' required.

def update(name, ipaddr):
  name = name + '.' + domain
  conn = boto.connect_route53(access_key, secret_access_key)
  changes = boto.route53.record.ResourceRecordSets(conn, zone_id)
  for rr in conn.get_all_rrsets(zone_id, 'A', name, maxitems=10):
    if rr.name != name or rr.type != 'A':
      continue
    change = changes.add_change('DELETE', name, 'A')
    for ip in rr.resource_records:
      change.add_value(ip)
  change = changes.add_change('CREATE', name, 'A')
  for ip in ipaddr.split(','):
    change.add_value(ip)
  changes.commit()

def main():
  import sys
  update(sys.argv[1], sys.argv[2])

if __name__ == '__main__':
  main()