If you're going to offer an open device (meaning you put your own apps on it, its just a regular machine in the traditional sense) to students and think that they will have some magic incentive to pay for that device - that thinking is flawed - as (even as HNers point out) they can spend money they were planning on already spending on a system they have total control over and more choices WRT its features.
However, if you were to partner and build a knowledge/content delivery platform which was the real value of a device - and the hardware was incidentally delivery mechanism, then you could begin to have something of value.
For example, an OS, apps and content designed to be together and be a part of the curriculum.
I think this is where Khan Academy can really make a revolution - especially if they have support from various directions.
Right now, Khan Academy has content organized by subject - and there is the beginning of a teaching/tracking platform which provides tools for tracking a students progress.
This is the idea that needs to be expounded upon and put onto any of these systems-to-students ideas such as the google laptop.
Google is already going after education and enterprise organizations to provide email and apps-for-domains.
They really need to look at Khan Academy as the vector for really getting into this in a meaningful way.
If we take the idea of Meaningful Use from the medical space, and create Meaningful Education and begin to put a lot of great thought into the education platform - we could change the world of education.
We need real platform development that accounts for the content, context and containers in such a way that we really utilize technology in an augmenting way.
Google's approach with this model is bottoms up - where we need more tops down.
There are far too many assumptions that providing technology without contextual content and tools will foster innovation etc. but really we have not seen a real thought-out approach to this problem.