OAL Wrapper Source Code
Yes, here OpenAL C++ Wrapper that was built and used for the Penumbra series as well as the upcoming Amnesia: The Dark Descent game.
Read through the TODO file for various known things that should be cleaned up / fixed.
Included are project files for Xcode, Cmake (for Linux).
We encourage everyone to contribute code to this project, so just sign up for a github account, create a fork and hack away at the codebase. We will start an Open Source forum on the Frictional Games forums as a place to talk about changes and to submit patches from your forks.