Hi Stephen....had to do a bit of investigating to get some of this info for you but hopefully it will help with some of your upcoming decisions for a Walt Disney World trip.
These dates might not be accurate for each year as the information is old but generally the Free Dining has been offered to some degree since 2005. They have targeted the times when the parks attendance is generally low with that being late August through September. The announcements of such plans have been around March and April. This year they added a quick service only plan from late 2011 through early 2012. With each year there have been special conditions or requirements and I did not include those as I'm not sure I can find that specific information. Obviously there are no guarantees to what they will have in place this year if anything and we have not heard any updates yet.
Here are the dates since 2005:
2005: August 21-October 4
2006: August 13-September 30
2007: August 26-September 22
2008: August 10 (UK only)/30-September 27
2009: August 2-October 3
2010 Valid Dates: Aug. 15 – Oct. 7, Oct. 22 – Oct. 28, Nov. 12 - Nov. 18, Nov. 27 – Dec. 2 and Dec. 10 – Dec. 21, 2010.
2011 Valid Dates: Jan. 1 – Jan. 5, Jan. 9 – Jan. 13, Jan. 21 – Feb. 3, Feb. 25 – March 3, May 27 – June 2 and Aug. 19 – Sept. 29, 2011.
Valid dates for this offer include:
2011: Oct. 2-8, Oct 23-Nov 5, Nov 13-19, Nov. 27-Dec 3, Dec 11-17
2012: Jan 8-14, Jan 22- Feb. 4, Feb 12-18, Mar 4-10, Mar 25-31.
Offer must be booked by October 29, 2011