This certainly took me by surprise. He had, by all accounts, a very successful run as Dean of Stanford Law School, and before that was a prolific and highly respected scholar. On a personal note, I'll add that he's always been a very helpful and candid correspondent about matters pertaining to legal education and legal scholarship. I wish him the best in his new venture!
UPDATE: I should note that Dean Kramer will succeed at Hewlett Paul Brest, another former Dean of Stanford Law School.