Harvard Law professor Charles Ogletree is working on a book about his friend and former law school student, President Barack Obama. Titled “Obama: Our First Black President?,’’ Olgetree’s oeuvre will focus on Obama’s evolution from “Hawaiian multiracial child to black American male.’’ It will be published by Basic Books. Ogletree, who still advises the president and will spend time with the first family during their upcoming Martha’s Vineyard vacation, was represented by John Taylor “Ike’’ Williams of Kneerim, Williams & Bloom. . . . Williams also reps Margo Howard, the longtime advice columnist known as “Dear Margo’’ and, before that, “Dear Prudence.’’ Howard, who retired this summer, is writing an advice book, called “Eat, Drink & Remarry: A How-Not-To,’’ to be published by Harlequin Nonfiction. Howard’s mother was Eppie Lederer, the woman known to millions of newspaper readers as Ann Landers.