Hayao Miyazake's next project will be "Gake no ue no Ponyo" (Ponyo On A Cliff). It is the story of 5-year old boy Sosuke(to be modelled after his grandson) and the Princess goldfish Ponyo who wants to be human.
The film will be created over 20 months for a release in 2008 (Japan) and likely 2009 for western cinemas. Miyazake drew the entire storyboard in watercolour and production began in October 2006. source: GhibliWorld.
And for those who don't know Hiyao Miyazake, I can recommend every single one of his films. IMDB entry for Hiyao.