Every Pokemon game has eventually had a later release with slightly more content than before. It seems that this is about to happen for Pokemon Black and Pokemon White, if a new registration is to be believed.
“PokemonGray.com has been registered by Melbourne IT DBS,” posted by ‘Joe.’ “The reason this is a big deal is because they are the same company that registered PokemonBlackWhite.”
If this is true, the question remains whether it will release for the DS or the 3DS.
Source: NintendoBuzz.com