While he was being interviewed by David Frost, Bill Nighy announced that he will be taking over the voice of Reepicheep in The Chronicles of Narnia: The Voyage of the Dawn Treader.  Reepicheep was originally voiced by Eddie Izzard.  He also mentions Harry Potter and the Deathly Hallows right after that.

Watch the interview below (starting at 5:26 in interview).  The movie will be released on December 10, 2010; a month after Deathly Hallows: Part 1.

Thanks NarniaWeb!