Drupal 7.10, a maintenance release with numerous bug fixes (no security fixes) is now available for download. Several major bugs, including one causing errors with the 5.x branch of Drush, have been fixed this release. See the Drupal 7.10 release notes for a full listing.
Upgrading your existing Drupal 7 sites is strongly recommended. There are no new features in these releases. For more information about the Drupal 7.x release series, consult the Drupal 7.0 release announcement.
After it's been pointed out to me that I was missing many themes, I realized that I had a bug in my logic and had only enabled themes that were not actively maintained.