Available from Apple as an iBook (search for the isbn 9781595000057) and Amazon (search for ASIN B007UP59Y0) for $2.99.
This was an experiment: Can I do a book of images, all with lots of fine little bits of detail, and format it within some reasonable constraints of file size and readability? Answer: Yes, but a lot of tricky photoshop work was required. On the iPad, in particular, you can enlarge all the images and see the little teeny tiny bits. Thank you, O people who helped us debug it; it now works great.
The final product file size is slightly over 8 MB, which among other things means Amazon deducts $1.18 from the amount they pay me for every copy sold (their download fee, paid by the publisher rather than the purchaser). One cannot get rich this way.
Apple has a different cost model. So also do Barnes & Noble and a couple of other places where it will be for sale shortly.
The next Hidden Knowledge book will be mostly text.