1. http://stackoverflow.com/questions/1224708/how-can-i-create-...

2. http://stackoverflow.com/questions/4134114/capabilities-for-...

I find it easier to trust Lua than similar facilities in other programming languages because the kernel of the language has a relatively simple semantics, so the TCB of a sandbox is lower, and the source is easier to understand than most other languages.

Note that sandboxing in Lua 5.2 has a still simpler semantics than for Lua 5.1 - few other languages evolve in a way that makes the language easier to trust.