As part of its package of new offerings, Apple announced it would offer an app that allows users to download and read e-books on the Mac computer. Up to now you could only do that on an iPad or iPhone. iBookstore has been around since 2010 but falls a distant third in sales to Amazon and Barnes & Noble.
It's been possible to read books on the PC for quite some time but the general response is "who wants to?" Sitting at a desk staring at a screen to read an entire book? Not likely, but don't burst their balloon, Apple is quite giddy with its new offerings at the moment (and yes, they still have great products even if iBookstore is a bit of a dog).