From the Library Journal, their Fall preview lists a third book of observations on art by John Updike, Always Looking: Essays on Art (Knopf). His first two: Just Looking (Knopf, 1989), and Still Looking (Knopf, 2005).
Also from The Library Journal, a listing for Saul Steinberg: A Biography (Nan A. Talese: Doubleday) by Deirdre Bair. This should be fascinating. According to the Library Journal’s listing, the author was allowed to “rummage through 177 boxes of never-before-seen materials to write this biography.”
Looking for more Steinberg? Harold Rosenberg’s Saul Steinberg (Knopf, 1978) and Joel Smith’s Steinberg at The New Yorker ( Abrams, 2005) are worth seeking out, as are all of Steinbergs collections.