Right now Disney has only acquired video rights for 8 Ghibli movies (except "Grave") and the global distribution rights for "Mononoke Hime". Disney will release English (and other language) dubs. The agreement can be expanded into other fields, such as games, CDs and merchandise in the future.
There are reports as well that, Walt Disney Company is in preliminary talks with Studio Ghibli to buy the Japanese animation studio, acquiring the rights to the studio's movie catalog and its wealth of characters. The transition is set to begin after the completion of Ghibli's two major productions, Hayao Miyazaki's Kaze Tachinu and Isao Takahata's Kaguya Hime no Monogatari, in 2014.
Although the details of the merger are not yet fully revealed, it is expected that Studio Ghibli will retain its autonomy in Japan, and continue to produce their own films with Disney's help.
Of interest, Walt Disney's ESPN unit has announced that it will shut down its 3-D production unit at the end of the year because of the cost and a lack of interest from customers.