A new Pokemon Wii game is in the works and is apparently going to be announced soon. The September issue of Famitsu magazine contains an interview with the president of The Pokemon Company, Tsunekazu Ishihara, in which he discusses HeartGold and SoulSilver. Towards the end of it, he says this:
I can’t go into details about it, but we’re also working on a Wii game. It should be announced soon.
The game could either be new WiiWare like an updated Pokemon Ranch or, more likely, an actual commercial Wii game like Pokemon Battle Revolution. We’ll find out soon! Thanks go to Dogasu and Pokeani for discovering this news story earlier in the month!