The entire post is worth a read, as most of Speirs' posts are, but here's the money quote:
Put simply, if you're in the business of making discrete hardware for the classroom you are in very serious trouble. Your business is about to be replaced by a $5 download from the App Store and the rest of your company's existence will be about trying to sell a refresh to your existing installed base.
I also love this bit:
Interactive Whiteboards are the next great Zombie Technology. The installed base is now so massive in schools that, like Internet Explorer 6, they will have a long, slow, lingering death.