Although Django's release cycle is generally date-based, we also try to keep our release dates flexible to account for bugfixing time. At the beginning of the development sprints at PyCon a few weeks ago, over 300 tickets were still open on the Django 1.2 milestone. Now it's down to 120 (we've been clearing out, on average, about ten tickets a day), but that's still a lot more than we're comfortable shipping; as a result, we're pushing back the final 1.2 release a bit.