I don’t have any information, but his email address can be found at the bottom of this page: http://www.earlyunitedstatescoins.com/about--contact.html I’ve emailed him before, and he did respond, so he may be able to provide details. And while I don’t collect bust halves, I’m sure that this will be a great book when he finally publishes it. I have his bust quarter and it is my favorite numismatic book.
First book came out years ago, so it would seem like the second would be out sometime soon. I didn't buy the first volume, because flowing hair and draped bust halves aren't really my area. I think the plan was to split the Capped Bust Halves into 2 volumes.
For anyone interested in my question his website still says that he hopes to have it out sometime this year. No new info, but while there I found 2 halves that I wanted more than he did so maybe I shouldn't have checked. LOL