Amazon, I don't know. They're ever so convenient and all, but they do do some loopy things - and I can't imagine it'll get any better when they're the only bookstore in the world. The latest oddity is that they have removed the price and pre-ordering details from Mirabilis Volume 2. However, the Book Depository (which Amazon of course bought this summer) are listing the book, which they correctly state will be released in just 12 days. So ample time to order it for Christmas - but only if you live in the UK and go to the Book Depository website. In an extra-strange wrinkle, Amazon US are listing the correct publication date (December 1st) but still haven't enabled pre-ordering - though perhaps that's just as well, as technically the hardbacks are only supposed to be available in the UK and Eire.
We're not the only title this has happened to. Amazon UK just de-listed Ed Brubaker's Criminal Vol 6: The Last of the Innocent and cancelled my long-standing order, saying, "Our supplier has informed us that this item is no longer available. This item has now been cancelled from your order." Yet there it is on Amazon US with a release date of December 21. Most peculiar, momma.

