"I’d love to chat with you about FORTUNE’s exclusive excerpt of David Kirkpatrick’s book on Facebook"
"note that the story stems from an exclusive excerpt in FORTUNE of David Kirkpatrick’s new book The Facebook Effect."
"once you’ve read the excerpts, please let me know if you choose not to post on one and not the other or both"
The use of the words "exclusive" and "on" seem to make it pretty clear that he was supposed to post ABOUT the excerpts. Their intent may be antiquated, but I think it was clearly communicated.