Yeah, thin clients have drawbacks, and they probably aren't going to take over the world, but this is a pretty sweet anecdote from Tom Wolfe on the K12OSN list:
This winter I was away, as I often am in the winter, for a couple of weeks and an electrical contractor working on an addition accidentally piped 220 VAC into three classrooms. Literally there were flames and smoke coming out of 20 P3 IBM Netvistas. Fortunately I had a stack of "spares" in our storage room, and the teachers, remembering my exhortations of "hey if it ever craps out just throw it in a pile and grab new one" took me at my word, and when I returned a week later it was like nothing had happened... Except that I had 20 destroyed workstations lying in a pile. All the labs were operational. Wow. How much did this cost the school? Well... how much was the labour cost of these teachers grabbing a new one and plugging it in? If they had been shiny new Optiplexes running Vista, the cost would have been massive, to say nothing of the down time until I replaced them.