It's a similar observation to the Inner Platform Effect http://en.wikipedia.org/wiki/Inner-platform_effect

Any project that runs some sort of external script would count. Soon a config file has some sort of conditional (#define grows #ifdef) and variables.

Also any project that has a VM (in the traditional sense) such as SCUMM.

It incorporates the notion that Lisp will do everything already, the code as data as code that Lisp gives you is a win that coders dismiss until it's too late and they have spent years learning C++

The browser.

Well, it's pretty formally specified now. (Also pretty fast.)

It's kinda sorta specified in English prose. I wouldn't call that formal, though.

Emacs? ;)