The book is titled Did I Inspire Darth Vader?: Life Through Letters. The grinning boy authored one side of each correspondence; various others (mostly famous people) wrote back to him.
The ad touts the boy as "the universally acknowledged...world correspondence champion" (!). He's apparently the Barbara Walters of the mails (snail & e-), eliciting thoughtful & revealing responses from all kinds of celebrities. From some excerpts, I get his modus operandi, what makes them write back: He conveys a perfect appreciation of some long-neglected aspects of their work, and then barely more than hints at asking some follow-ups. They can't resist.
The collection's title comes from his first letter to Lucas, a letter declaring how the whole series is really about the Vader in each private guilty soul -- how we each grapple with senses of entitlement, wills to power, relentless ambitions...
So young! So driven!
Another amazing thing: It was a very vivid dream. That's why I can't point to anything more about the book.