I saw...
Adventureland:
-Lilo & Stitch (near the entrance to Adventureland inside building near Aloha Isle)
-Jasmine & Aladdin switching with Genie & Abu (near Aloha Isle)
-Peter Pan & Wendy (near Pirates of the Caribbean)
Frontierland:
-Country Bears and Brer Bear (roaming streets)
-Woody & Jessie (inside Diamond Horseshoe)
Fantasyland:
-Belle (in her Christmas dress) & Beast switching with Snow White, The Prince (near it's a small world & Peter Pan flight)
-The Tremaines (Ariel's Grotto dance party)
-Donald switching with Scrooge (tree lot near Tea Cups)
-Alice (near Tea Cups)
Toontown:
-Mickey in Christmas outfit (his house)
-Minnie in Christmas outfit (her house)
-Cinderella, Prince Charming, Aurora, Prince Phillip (Toontown Hall of Fame)
-Tinker Bell (Toontown Hall of Fame)
With the Fantasyland expansion I'm guessing some characters will be in different places this year..