I've started a Google code project for a Lua implementation of the algorithms from the Stuart Russell and Peter Norvig book Artificial Intelligence: A Modern Approach.
I'm planning on working through the book, chapter by chapter, and creating Lua implementations of everything. In general, I'll try to stick to the spirit of the algorithms presented in the book, though there may be ways to implement them it in a more elegant and concise fashion using Lua's unique strengths.
Emphasis too will be on code that is "production ready", meaning that it can be readily incorporated into other projects.
The style of the code will vary. If it makes sense to use OO style, great. If functional seems a better fit, then I'll use that instead. I'm not as dogmatic about that kind of thing as I used to be.
I'm using a Mercurial repo, so if you'd like to contribute, just clone it and get going!