December 1, 2012:
Feature freeze. No new features are allowed (unless specifically exempted), focus turns instead to API and UI clean-ups and polishing of existing features.
February 1, 2013:
Code freeze: focus on bug fixes, stabilization. No API changes, instead focusing on bug fixing, preparing for release, and getting the count of critical bugs down to 0.
August, 2013 (DrupalCon Europe 2013): Drupal 8 released