From a GigaOm Report by Kevin Tofel:
Siglio Press is offering 250 signed and numbered copies of a limited edition print book that requires a webcam and computing device to actually be read. Why? The print pages — a back-and-forth series of letters between two lovers — only have glyph-like symbols on the page. The book contents appear in virtual reality images on screen when the book is held in front of the webcam.