Apple has just recently announced like from WWDC 2013 that iBooks will be coming to OS X. This means that all the books you've purchased on your iPhone or iPad will now be readable on your Mac as well.
You'll be able to access the iBookstore natively through iBooks in OS X along with tabs along the top that lets you sort and create collections just like you can in iOS.
Textbooks will also be interactive via iBooks for OS X. Gestures such as pinch to zoom and interactive table of contents. This means taking notes and using textbooks will become much easier on your desktop computer, complete with flash cards.