The issue that Amazon was cracking down on was folks who went to Google Books, found some work like *"The Inventions, Researches and Writings of Nikola Tesla, With Special Reference to his work in Polyphase Currents and High Potential Lighting" and then downloaded it from Google and uploaded it to the Kindle store , 
 http://books.google.com/books?id=bhrreukJiLgC&printsec=f... is the Google Books version
 http://www.amazon.com/Inventions-Researches-Reference-ILLUST... is the Amazon Kindle rip-off version.
Also argued to be 'uniqueness' by a Professor at Miami School of Law: http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1906047
Somehow I don't think Walter will go out and sue people if they make copies of this e-book but I do expect that should he do so he would prevail.
So off list one of the Gutenberg folks pointed out this exception:
"Chuck they get away with this by adding a new introduction or critical essay to be book, delete that and its back to public domain."
And notes that every republished work by various publishers that use public domain material does add an introduction or a bit about the author to establish that Copyright.
So I take it all back, Walter you should introduce your book with your thoughts on how appropriate it is and then charge what ever you want :-)
I also have a crapton of out-of-print books that are available nowhere, that I would put online for free if it weren't for the dang copyright laws. Some I have attempted to find the copyright owners, but I just find deadends.
It's really a sad state of affairs.
My personal opinion (and I make my living selling copyrighted software) is that copyrights should be good for 20 years. After that, you can keep the copyright going only if you're willing to send in a $1000 fee every year for each copyright, and that fee should go up a percent a year or so.
That'll put all the abandoned works into the public domain.