I wonder if iPhone's browser does XML and XSLT, like all modern browsers do?
It happens that XSLT is Turing complete, and the browser can certainly download stuff from teh internet. This could mean that merely embedding the browser into your iPhone app effectively turns it into an interpreter for programs downloaded from anywhere. Sure it's sandboxed but technically that shouldn't matter. And I'm sure you could introduce hooks to the browser from native side, to make something interesting out of it.
It happens that XSLT is Turing complete, and the browser can certainly download stuff from teh internet. This could mean that merely embedding the browser into your iPhone app effectively turns it into an interpreter for programs downloaded from anywhere. Sure it's sandboxed but technically that shouldn't matter. And I'm sure you could introduce hooks to the browser from native side, to make something interesting out of it.