I checked again today, and it looks like the Amazon page for Arrival of the Traveler is up, but not entirely put together yet. You can check it out here: Arrival of the Traveler (Paperback).
I've been checking in every so often to see what's going on over at Amazon, because I released the paperback on the 20th. This morning, the page only had basic information, but not price, and the book was not yet available. Now, it appears to have the price, and be available for purchase, but the cover image hasn't been added yet. Amazon will link the paperback and the Kindle edition together onto one browsing page automatically; otherwise, the help pages have told me to send them an email.
Exciting news! I have to admit I was a little disappointed when the book didn't appear instantly in Amazon's listing, but seeing it now is very gratifying. Learning about the publishing process has been an unexpected bonus of getting these books out there.