Korokoro manga magazine revealed today that a new game in the Pokémon series, called Pokémon Ranger, will be released sometime in 2006. No other information, such as system, was available.
In other news, more information about Pokémon Diamond/Pearl was revealed from Korokoro. These two Nintendo DS games will be compatible with the GBA titles, and will allow you to transport your pokémon from the GBA games to the DS games. Specific new pokémon types weren't described exactly, but it was said there would be "lots" of new pokémon as well as the introduction of various new types from the different Pokémon movies.
Pokémon Diamond/Pearl are to be set in a completely different universe than previous Pokémon titles. They are said to take full advantage of all the abilities of the DS, including 16-player wireless multiplayer. The games are scheduled for a simultaneous release sometime next year in Japan.