Certainly in the UK, Macs in school are barely even heard of in schools.
I think breaking into the Education market is a very smart move. From my experience (and I'd wager in the states), it's largely on PCs, rather than Macs that students/staff are using.
By providing the incentive to buy textbooks through Apple, from a networking point of view it encourages investing into the desktop/laptop line as well.
I really hope the textbook initiative takes off, I'd love to see more textbooks on iBooks. At the moment, I find there's a very limited selection and while I was at University I didn't find the information on the web for my degree at the time, great either. I hear what people are saying about what having an actual book is good for, but in many ways this makes books so much more accessible to those that need it. As a student with a disability, I hated lugging the bastards around and spent a lot of time photocopying stuff I would need. Not to mention being roped into buying books as well, which were used mainly for reference so were essential but in the end leave a hole in your wallet, lots of space taken up.
Now as a graduate - approaching my 2nd year after graduation, I've found that my degree suffered as a result. I thrived on online resources and succeeded through using those through high school - but the reliance on physical textbooks were counter-productive and in ways, affected my degree as a result.
Since I'm now in work, I find myself actually redefining my education and looking to redo the university level stuff all over again. But its difficult and the digital market isn't there yet in terms of the materials available and the quality of them too. The thought of interactive content in e-Books is great, hopefully this will propagate towards degree level textbooks too.