This is obvious. That's what they are for. But on the iPhone the tedious stuff is dealing with the APIs. And you would not gain much just by wrapping them with another language.
> The real problem here is that interpreters for the iPhone seem to be a gray area at best (see discussion elsewhere here).
As I have stated many times in other threads, there are apps (published on the Appstore) written with squeak smalltalk, games made with Unity (which uses javascript on top of Mono for scripting the game logic) etc.
What you can't do is to expose the interpreter to the user or to make it run code downloaded from the web.
Even if this wasn't the case, how could Apple even know, for instance, that I have statically compiled the Lua interpreter and used it to script part of the logic of my app?