The monthly security release window for Drupal 6 and Drupal 7 core will take place this Wednesday, October 17.
This does not mean that a Drupal core security release will necessarily take place on that date for either the Drupal 6 or Drupal 7 branches, only that you should prepare to look out for one (and be ready to update your Drupal sites in the event that the Drupal security team decides to make a release).
There will be no bug fix release on this date; the next window for a Drupal core bug fix release is Wednesday, November 7.
The release windows for Drupal core are a newly-instituted policy. For more information, see the documentation on release timing and security releases, and the discussion that led to this policy being implemented.