Any sources for that? I know Lua is often used as a scripting language in 3D games since it is very easy to embed a Lua interpreter into your game. If you haven't seen it, you should take a look at the lua source code. It's beautiful.

Essentially, you are making a nice internal API to your engine objects that you can manipulate, and experiment with, on a higher level without recompiling your application all the time. Python is also nice for this purpose (see OGRE 3D), but it's not as lightweight as Lua.

So in a sense, it's better to use Lua for parts of your engine that will change a lot, depending on what aspect of the engine you are a focusing on at the moment (like tweaking how the enemy A.I. works, for example). This is especially useful at the prototype stage of your application.

Is that what you had in mind, or am I mistaken?