Using database transactions with Drupal unit tests

Recently I've been experimenting with running unit tests for Drupal from the command line (with PHPUnit, not SimpleTest). One thing I tried was creating an entirely separate test database to hold test data, and also running each unit test in a separate database transaction in order to speed up testing, and to make it easier to handle test data.

If anyone is interested see: http://patshaughnessy.net/drupal-test-database

Would this idea help anyone with writing and running their Drupal unit tests? What else would be helpful for the Drupal community to have to encourage more use of unit testing and make it easier?