A company named Adesso Albums have created a new Photo book named YOURbook. YOURbook makes use of the Polaroid PoGo and other similar ZINK based printers and allows you to create an instant photo guestbook.
As well as producing YOURbook, Adesso Albums have created a bunch of other photo albums specifically for weddings, baby, birthdays, graduations etc... that allow you to create the guestbooks instantly (like pictured below).
It's not a bad idea at all and great for capturing the moment and preparing it right there and then.