I'm afraid
these things could give a whole crop of kids totally the wrong
 idea about what embedded programming is.  Using a familiar platform is neat
 because it means you can start from knowledge you already have but running a
 full-blown timesharing OS just to control a few blinkenlights or whatever is
 morally wrong. 
 Ubiquitous computing is not morally wrong.
 There is nothing wrong with abundance.
 Under this reasoning, we should arrest anyone with more food in their
 cupboards/pantries than they can eat in a day.
 Nonsense.
 There is nothing virtuous about scarcity. 
 
Acutally, I have found time and again  that simple systems (which doesn't
necessarily mean minimal component count) are more reliable than
complicated ones.
If you _need_ the power of an ARM CPU and a multitaksing OS, then that is
most certianly the way to go. If you just want to toggle an LED on or off
when you hit a switch, you might well fidn a PIC, or a 7474 D-type, or a
couple of cross-coupled transistors to be a superior solution.
Andd by never seeing the simple solutions to problems, you never think
about them when you have to design soemthing.
-tony