Illustrator Loren Long, who leaped into the limelight last week as the artist for Madonna's second children's book, Mr. Peabody's Apples, has just signed a five-book deal on his own, with Philomel Books in the Penguin Young Readers Group. President Doug Whiteman signed him directly for the books, one or two of which Long may write himself, His editor will be Patricia Gauch, and the first of the books is due in 2005. Long's style has been likened to that of Thomas Hart Benton, with a dash of Norman Rockwell nostalgia, and Whiteman said his work had admirers at the house even before his Madonna connection was disclosed. Long is also the illustrator of, among other titles, I Dream of Trains (S&S, Sept.), written by recent MacArthur Fellowship winner Angela Johnson, and The Day the Animals Came: A Story of St. Francis Day by Frances Ward Weller (Philomel, Aug.).