The Times online just ran a piece on Alice Walker's estrangement from her daughter Rebecca. Walker does not come out smelling like roses. She apparently ignored her daughter for years, running off to writer's retreats and Tracy Chapman's house, while her daughter languished ignored at home, pregnant at fourteen and high on God knows what. Then, a few years ago, she sent Rebecca an email formally ending their relationship. That's dark stuff.
But it's just another example of why we should trust the art and not the artist--the feminists who call John Updike (and many others) a sexist pig should keep Walker's example in mind. We don't canonize authors because they were good people but because their books are beautiful/important/moving/deep. I've got no doubt that The Color Purple should be in the canon--not just the "African-American" or "female canon," but the big one, alongside Homer and Shakespeare and Hemingway, and Walker's being a terrible mother or a terrible person has no bearing on that decision.