Pokemon Diamond & Pearl
The next Pokemon anime series is coming to Japanese TV this Fall, a guessed date being on September 28. It will be called "Pocket Monsters: Diamond & Pearl" & will focus around the new Diamond & Pearl Pokemon games for the Nintendo DS. The new series will star the female trainer from those games, & it is currently unknown if any other Pokemon characters will be part of the series. Expect the dub to reach America around 1 year later, in Fall 2007.
Source: http://serebii.net/index2.shtml