This is based off of the mantis connect soap api. Currently it just supports viewing a project via mantis/project/%project_id/issues or viewing an issue via mantis/issue/%issue_id. Look for more features to come in the next week or so.
First release for drupal 6 with single sign-on enabled for mantis installed in an external mysql database (mantis in the same database as drupal should work, but is untested), external postgresql will come very soon.