It's not free dining, but reduced price dining--essentially the adult meal plan was offered at child prices for people who also purchased a resort room & park tickets with the stay/play/dine package. That deal had to be booked by Dec. 31, but if you're trying to understand the restaurant crowds, it will probably have an impact that is similar to free dining.
We received a pin code for free dining from January 2nd-March 7th. We are now going because of this. I know of several others on the board who received the pin as well, so there is some free dining, but I do not believe it has been offered to the general public.
There is no current general public free dining offer that includes any dates in 2013. There was a Stay/Play/Dine package offer available to the general public, but while a discount, it was not free dining. There are bouncebacks (you must already be at WDW to book these) and PIN codes (you must personally receive one to use it.)