vicnmickey,
The "Hidden Mickeys" book is scheduled for general release to bookstores in early April. It sounds like the major bookstores may have them available now from their websites. The publisher may have the book available from their website: intrepidtraveler.com. The above offerings are possible because the printer had some advance copies made.
The book is organized into six different scavenger hunts for Hidden Mickeys: one for each major theme park, one for the resort hotels, and one for the rest of WDW. Each scavenger hunt has "Clues" to find the HM's in a challenging but efficient way and "Hints" to find each HM if you need more help. For example, to find all the HM's on Test Track on one ride would take some preparation and luck, so I would look at the Hints for each one so I maybe could catch them all. Otherwise, you might have to do Test Track a few times to spot all the HM's.
Hidden Mickeys also change. The Space Mountain HM's were in the preshow newsreel on the overhead monitors at the loading dock waiting queue. I was there a few weeks ago, and the monitors were gone! I e-mailed Disney, and they replied and told me the monitors would probably not be replaced. But you never know with Disney!
Thanks for asking, Steve
Steven Barrett, author of the "Hassle-Free Walt Disney World Vacation" and the soon to be released "Hidden Mickeys" book