We just went in December. We were there before Christmas (flew home on Christmas Day). I think the park hours changed right after we left but I can tell you what it was like when we were there.
All of the parks opened at 9:00 a.m. The Magic Kingdom closed at 7:00 p.m. on nights when they were having Mickey's Very Merry Christmas Party (Mon, Tues, Thurs, Fri). On Wednesday's and weekends they stayed open until 11:00 or 12:00.
At Epcot, Future World was open until 7:00 p.m. World Showcase was open until 9:30. But, both times we left Epcot after Illuminations (around 10:00 p.m.), we noticed some of the Future World rides were still operating.
MGM was open until 8:00 p.m. Animal Kingdom was open until 7:00 p.m. Again, I'm pretty sure these hours changed starting on Christmas Day.