from Garner's Usage Tip of the Day:
it is I; it is me. (2)
Those with even a smattering of French know that "It's me" answers nicely to "C'est moi." Good writers have long found the English equivalent serviceable -- e.g.:
o "It is not me you are in love with." Richard Steele, The Spectator, No. 290, 1 Feb. 1712.
o "But Silver . . . called out to know if that were me." Robert Louis Stevenson, Treasure Island 72 (1883; repr. 1985).o "Begin talking out your thoughts on paper as if you were explaining a concept to a friend. Imagine that it's me." John R. Trimble, Writing with Style 22 (2d ed. 2000).
E.B. White told an amusing story about the fear that so many writers have of making a mistake: "One time a newspaper sent us to a morgue to get a story on a woman whose body was being held for identification. A man believed to be her husband was brought in. Somebody pulled the sheet back; the man took one agonizing look, and cried, 'My God, it's her!' When we reported this grim incident, the editor diligently changed it to 'My God, it's she!'" E.B. White, "English Usage," in The Second Tree from the Corner 150, 150-51 (1954).
Similar problems arise in the third person, as in "it is him." When the contraction appears, Newsweek makes the phrase "it's him" -- e.g.: "Rostenkowski simply signed an expense-account voucher for stamps that Smith converted into cash. The first time he says he witnessed the alleged scheme, in 1989, 'I was no doubt taken aback when I saw his [Rostenkowski's] name on the [$2,000] voucher. I couldn't believe it was him.' Most Democrats on Capitol Hill still can't believe it's him." Jonathan Alter, "Rostenkowski Reeling," Newsweek, 2 Aug. 1993, at 20.