List of things that don't fit in somewhere else.
New stable releases of Drupal core are scheduled for the last Wednesday of each month. A new release will only come out on this date if it's deemed by the Drupal core maintainers to contain enough important bug fixes to warrant a release; if not, you're safe until the next month! :)
If a release is warranted, a "code freeze" will be called a few days prior to the release date, and the impending release will be announced via the @drupal Twitter account and Planet Drupal. This makes a great time to update to the latest code in the branch for your version of Drupal, and help make sure the code is solid!
Exceptions to this schedule may be made in case of security vulnerabilities being actively exploited in the wild, or severely critical bugs that prevent Drupal from being used.