Drupal 7.14 is now available, which contains bug fixes as well as fixes for security vulnerabilities from Drupal 7.13.
Drupal 6.26, which fixes known bugs (no security issues) is also available for download.
Upgrading your existing Drupal 7 and 6 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, more information on the 6.x releases can be found in the Drupal 6.0 release announcement. Drupal 5 is no longer maintained, upgrading to Drupal 7 is recommended.