Via OSNews, here's an interesting-looking project. Alky purports to be a binary translation layer for programs running on non-native operating systems. From the website:

We are focused on high-end gaming at the moment, though we will support other applications in the future. Our binary translation layer is already working fully for OS X and Linux support is in progress. Of course, Windows applications use a very different set of libraries from Linux or OS X applications so we are also working on a library called LibAlky that will provide those Windows libraries to the application.

Basically, that means it's only the various linkers and loaders that are working right now. It'll be interesting to see if they can get native libraries translated, but most games these days rely more on custom libraries than standard system calls. This might be one to keep an eye on.