-- New York Times obituary here
-- Appreciation (A. Goldhammer) in New Republic here
-- Harvard Center for European Studies press release here [pdf]
-- Hoffmann festschrift (Ideas and Ideals, Westview Press, 1993) here
Added later: For previous mentions of Hoffmann on this blog, see, e.g., here (quoting his 1977 essay "An American Social Science: International Relations") and here (quoting a 1995 article of his in Foreign Policy).
Added still later: Peter Gourevitch on Hoffmann at Duck of Minerva (here), which links to other things, including a piece by Gary Bass at Foreign Affairs online that I haven't read yet.