From The Walt Disney Company:
Roy Edward Disney, son of Disney Studios co-founder Roy O. Disney, and nephew of Walt Disney, passed away today (12/16/09) at Hoag Memorial Hospital Presbyterian in Newport Beach, California, following a year-long battle with stomach cancer. He was 79 years old. Disney was a successful businessman, philanthropist, filmmaker, and award-winning sailor, who played a key role in the revitalization of The Walt Disney Company and Disney's animation legacy. He was associated with the Company over a 56-year period, and from 1984 – 2003, served as vice chairman of the Company's board of directors, and chairman of the Studio's Animation Department. In recent years, he held the title of director emeritus and consultant for the Company.
You can read the rest of the Disney statement here.
There is also a lengthy piece by the Los Angeles Times here.