The only thing I know of now that will be closed in January is It's a Small World. It will be going down for a 9 month refurb. Otherwise, HM will be closed for a week or so as they take out the Nightmare before Christmas overlay.
well, for example,
Fall 2006 ~ Matterhorn went down from Sept 4 --> Dec 15th.
Spring 2007 ~ Splash Mt went down from Jan 26 --> May 20.
Fall 2007 ~ Riverbelle Resturant went down from Sept 4 --> Dec 10 (guessing)
Spring 2008 ~ unknown...