Yes they are, we were there 2 years ago thanksgiving week (well the friday b4 to the friday after) and most of the decorations are up that week, with them all done the day b4 thanksgiving! Make sure you go to MGM to see the Osborne lights (right up the street of america next to the sci-fi diner) The whole thing is amazing to walk thru (not giving all spoilers!) And be sure to stop in the lobby of the Grand Floridian (their tree and gingerbread house r amazing!) There is also a huge tree in the front entrance of each park and one huge one in the front of DTD!!!!
have fun! Maybe I`ll run into you, we`ll be there the 27 & 28th to end our cruise with a few days in the parks to avoid the high airfare out of orlando!