You can install and then call Moodle's "webservices":
- http://cipcnet.insa-lyon.fr/Members/ppollet/public/moodlews/
- moodle.org/mod/forum/discuss.php?d=67947
Also, call Moodle from MOSS:
- fraserelder.blogspot.com/2009/03/moodle-integration-solution.html
or the new Moodle 2 Web Services:
- docs.moodle.org/en/Development:Web_services
- moodle.org/mod/forum/view.php?id=6971
Moodle can integrate well with Google Sites/Apps ,Joomla ,Drupal and Wordpress (SSO, Web Services...)