An update for anyone who cares...
I did look at the web site for hiddendoor.com . Nice stuff but lots of
$$$$. Too much for my limited budget.
I saw mention of the SOSS hinge and mention of a Pivot hinge but they
protected themselves (rightly so I guess) by not showing you how they use
the hinge in their products.
I have googled for plans but haven't found any. I went to the soss hinge
site and looked at the hinges. Never seen them before and they look to work
pretty well! Didn't see any documentation on applications. Not being a
professional door installer, I'm not sure how to use these though.
My guess is that I'll look into using regular hinges. Maybe more of them
along the length of the jamb for the bookcase and somehow hide the knuckles.
The StanleyWorks web site had lots of hinge types. From what I'm seeing,
hidden door bookcases work really well in the movies. Practical
applications are a bit tougher.
I did see in some DYI newsgroup somewhere where someone had used black pipe
and bearings, which is what I had originally thought about doing! The person
who saw this was a plasterer and thought the idea clever when he saw it
work. He unfortunately, never took pictures of it. He said he wished he
had.

Ah well, back to the drawing board.
-TheKidd