Somewhere on TFL, I've seen an email address for PR. You might check the Q&A here.  It does at least have the address of his blog.

I think it would be very helpful to others here if we had a thread on errors in the book. I would love to know of any errors before I start a bread. There is a similar thread for Daniel Leader's new book. I know that if I purchase that book in the future, the errors thread will be the first place I look. A simple title like "Errors in Peter Reinhart's Whole Grain Baking" would be easy to find.