I agree!! Of course my first thought is what it would have told us about Atlantis.
http://news.nationalgeographic.com/news/2001/08/0806_wirelibrary.html
Likely nothing. The main enterprise at the library was copying scrolls. Whatver they had would have eventually been loaned out in copy and would possibly be found elsewhere such as at Naples, and most of what they had postdated Alexander.