In addition to Goro Miyazaki's Gedo Senki (Tales from Earthsea), Studio Ghibli have announced that they are working on another movie for release (in Japan) in 2006; Night of Taneyamagahara is based on a 1924 play and will be directed by debutant Kazuo Oga. Oga's impressive anime C.V. includes working on the background art of many of Ghibli's highest profile movies (Sprited Away, Princess Mononoke and Howl's Moving Castle to name but a few).
More information can be found over at Ghibli World.
More information can be found over at Ghibli World.