Considered perhaps the best Russian poet of our times, Joseph Brodsky, an involuntary exile since 1972, has resigned from the American Academy and Institute of Arts and Letters in protest of the recent induction of Soviet poet Yevgeny Yevtushenko. In his letter of resignation, Brodsky wrote, ``I cannot in good conscience sustain membership in an organization which has thus so fully compromised its integrity.'' ... James A. Michener's ``Legacy'' (from Random House in September) will be a mercifully brief novel that starts with the Iran-contra scandal and ends with a paean to the Constitution. Timely. ... Business books are big business, so much so that there's a market for Executive Book Summaries. They're published in Bristol, Vt., and cost just under $60 a year. Each month's issue boils down two or three of the best-selling business books into eight-page, bite-size presentations. Great for the commute.... Deborah Davis's controversial biography of Katharine Graham, chairman of the Washington Post Company, is back in bookstores after seven years in the trash heap. Published this time by National Press of Bethesda, Md., the revised and expanded edition of Katharine the Great: Katharine Graham and the Washington Post includes copies of documents that appear to link the Post's executive editor, Ben Bradlee, with the Central Intelligence Agency during the '50s. The book also names the person the author claims is Watergate's Deep Throat. The original publisher, Harcourt Brace Jovanovich, recalled 20,000 copies of the 1979 version and shredded them after Bradlee objected to 39 ``errors.'' Davis sued and settled for $100,000 in 1983.