This is really sad. Tom Mankiewicz was responsible for a bunch of legendary movies, some of my personal favorites of all time. Like Superman 1 & 2, Live and Let Die, Diamonds Are Forever, The Man with the Golden Gun, Ladyhawke & Dragnet. He passed away at age 68 after subcumming to pancreatic cancer.
AICN has a great piece written up highlighting Mr. Mankiewicz's numerous great writing achievements along with some of the ones that he also directed like 1987's Dragnet.
http://www.aintitcool.com/node/46015.