No epub? Google offers ePub right now. I have Voltaire's Philosophical Dictionary (not by him, about him) in my Google Books and it offers me an ePub download:
http://books.google.com/books?id=TBc...age&q=&f=false
The browser display seems to be a scanned PDF image file, and I have not tried it on my Reader yet, so maybe it is just images, but it does offer the option of an ePub download now.