Re-schedule all tasks in a list
Just as you can re-assign all tasks belonging to a list, you can now also re-schedule them. Just navigate to your list and the option is there at the top. This will re-set all tasks in the list to the same date. This is not the same as the move tasks feature which lets you shift the due date of all tasks by a number of days you specify. Hopefully the combination will provide useful options in different circumstances.
Thanks again to MazzaRC for this suggestion, amongst others! I really appreciate all suggestions for improvements to the site!