Apple just released an update for their professional photo management software, Aperture. Update 2.1.2 "Improves the printing quality of books ordered through the Aperture printing service." It sounds like this would be a welcomed update by many professional users who rely on photo books and prints ordered through Aperture.
You can download this update through Software Update (Apple menu > Software Update), or by downloading the installer package from Apple's update download website.
Update: Apple has just created a download page for the Aperture update.
Thanks for the tip, Nik!