This has many techies salivating:
"There are also three programming environments of different
degrees of sophistication. Incredibly, one keystroke reveals the
underlying code of almost any XO program or any Web page. Students
can not only study how their favorite programs have been written,
but even experiment by making changes. (If they make a mess of
things, they can restore the original.)"
This has a long tradition, actually. The "Lisp" and "Smalltalk" worlds had this long ago, but Windows and Unix won in the market.
They went with Python, which was also used for letting gamers program Civ 4. Something for the techies: http://dlweinreb.wordpress.com/2007/11/20/xo-the-next-lisp-machine/
Tayssir