I fired up Chromium OS from a USB key on my laptop yesterday. Works pretty well for kicks, except no wireless on my ThinkPad. The big Aha moment is when the initial login screen wants your Google ID rather than a local one, and then automatically logs you into your GMail and Google Calendar in the first two browser tabs. It feels like you're logging into your office LAN, except your office is now the internet. And it doesn't belong to your office, and not quite to you either.
It reminds me a little of the first time I used Office 95. Each part of it was reasonably well executed, but what was exciting was that Word, Excel, etc. were clearly meant to work together. At the time, that was a big deal. Chrome OS has that feel too... like the pieces are pulling together. And it does give you a little Microsoft-y chill... Google is selling you Google Calendar exactly the same way Microsoft sells Outlook (and Apple sells iCal). Of course, most of the above are "free," (as in beer) so it is a peculiar type of sale.
For schools that have already decided they're ok with using Google services for public business, Chrome OS devices will be a no brainer. Using the whole stack will really start to draw down the old TCO, in every dimension. I'm ambivalent about becoming too Google-dependent.