One of the things I really enjoyed about the Internet Archive Open Library project was the software they used to attempting to determine whether works they were scanning were or were not under copyright. It was an elaborate set of questions and answers with access to some copyright databases. In contrast, unless I’m mistaken, Google Books just draws a line at 1923 and assumes everything after that date is in copyright. This includes government information which as you know is made with tax dollars and generally in the public domain. So why does Google Book Search treat all post-1923 books as under copyright? Just over-cautious?