IGN talked with Miyamoto and this is what he said about Animal Crossing Wii:
"The Animal Crossing team has been very busy working on a variety of different projects. Actually, the Mii Channel was put together by the director of the most recent Animal Crossing game. His name is Mr. Nogami. Recently he said he really wants to get back to work on Animal Crossing again, so hopefully we'll be able to show something to people before too long."
I guess we're going to have to live with just this bit of information for now.