I have an ulterior motive for starting this topic: I'm turning in an article today on 2008 family films and want to add a coda looking forward to 2009 without missing anything too obvious.
Pixar's Up, of course, heads the list, along with the October 3-D release of Toy Story. Harry Potter 6 is obviously highly anticipated by many, and there are some others, including Spike Jonzes's Where the Wild Things Are, Wes Anderson's The Fantastic Mr. Fox, Disney's Race to Witch Mountain. Another Ice Age, another Night at the Museum.
What else should I mention?