Yup, you can now read all 2,293 (which really boils down to about 1930) books from Elder Scrolls Online on the Imperial Library. They are fully integrated into the search and our topic tagging system (which will itself get an overhaul soon).
There are a lot of really good books in there, some of which we'll be highlighting in the coming days. Get crackin'!
http://www.imperial-library.info/books/online/by-category
http://www.imperial-library.info/books/online/by-author
http://www.imperial-library.info/books/online/by-title