All three parts of Jim Newton's series on Justice William Brennan's memos are now available on Slate:
Part One: Brennan on Burger (and the death penalty);
Part Two: Brennan on Abortion (and U.S. v. Nixon);
Part Three: Brennan Dishes on His Colleagues (and on Warren's legacy).
Rick Hasen has some comments on part three, and some of the memos' distrubing disclosures, here.