We're eating at Boma for Thanksgiving.
I agree with the other poster, things are going to be very limited at this point. Do you know where you want to be on Thanksgiving, which park/area, or does it not matter?
If you know where you want to be, I'd call Disney Dining (assuming you want to eat on property), and ask what's available for Thanksgiving Day in that park. Another thing I've heard about people doing is to have the "Thanksgiving" meal on Wednesday evening, and do counter service on Thanksgiving day. From what I've found about previous years, it seems that a lot of the resort food courts will offer a traditional Thanksgiving dinner as an option.
Good luck, I hope this helps!