Today has released Drupal 7.5 and Drupal 7.7. Do you feel strange why there are two versions released simultaneously? is because each version has a different purposes.
For Drupal 7.5 only contains a security fixes in Drupal core, while Drupal 7.7 contains bug fixes and security fixes, so you can decide whether simply want to improve safety on the Drupal core only or choose to install a version that contains security fixes as well as bug fixes.
How about the Drupal 7.6?
Nothing is different between versions 7.6 and 7.7, its only a fixed VERSION string. For more details about both release you can read the Drupal 7.5 changelog and Drupal 7.7 changelog.
Download Drupal 7.7 here.