Parent post got part way there - yes, the web and HTML is a great way to deliver content.
However, the key here is what _software_ the students will be expected to run in order to _author_ content.
For those of you Windows zealots that haven't bothered to try a Mac, please be aware that it's perfectly possible to run MS Office. But it's also possible to run Apple's iWork suite, or OpenOffice. Or Google Apps in the browser.
It's very common for IT departments in all types of organizations to choose to support a single OS platform. It's equally common for competent power-users in those organizations to opt-out and use the platform of their choice - but to take on the responsibility of self support. Those policies are usually written in draconian tones "we only support X, you must use X" - but in practice it's easier to keep the power users occupied self-supporting their unapproved platforms than have them hacking away at your standard ones.
The thing that makes or breaks this situation is the software platform chosen. I'd be a lot more concerned about requirements to submit classwork in native Pages (the iWork word processor) format than I am the choice of official supported hardware. If the software and data formats are reasonably compatible with multiple platforms, things will work out.
It's fine for them to choose a supported platform. It's not fine for them to make it gratuitously difficult for others to self-support. If a group of determined parents and students want to use Linux environments instead, it should be possible - not supported, but possible. Similarly if they want to have a Windows group, so be it. This school hasn't made the mistake of blocking this - yet, or at least according to the data available to us.
Now, for those who haven't actually laid hands on a MacBook side by side with an equivalently equipped other laptop, you really ought to do so before asserting the value for your dollar spent. Heck, run Linux on both for a week, taking the OSX out of the equation, and see what think. It's premium hardware, and sometimes that's worth it and has a lower TCO. Looking only at the initial purchase price is foolhardy.