Mac Apps on Linux?

The WINE project is an "Open Source implementation of the Windows API on top of X and UNIX". In layman's terms, it means it lets you run Windows programs on Linux. In my personal opinion, I would say this project is a wild success, especially with the advancements made to it in the last year.

With the release of Apple's OS X for Intel x86-based processors, OS X applications are being released in a different "format" to run on these new processors. After reading about this many times, a thought occurred to me: x86 executables (programs) instead of PowerPC (the old processor type) executables means that if one wanted to hypothetically try to run OS X applications on Linux, it would no longer require an emulator. Then it occurred to me.

I might be wrong, but I believe it should now be possible to implement an OS X API on top of UNIX, exactly like what WINE did to the Windows API.

Sure, OS X applications are in a different non-ELF (non-Linux) binary format, but neither are Windows apps. Can anyone think of any real reasons why this shouldn't be possible now? (Again, I might be wrong, but some of the GNUStep APIs might be re-usable in a project like this...)
Granted, it would definitely need an enormous effort, but it would be absolutely incredible if Linux could run both Windows and OS X apps.

(And for those who are confused, this is approach is totally different from that of Mac-on-Linux or VMWare, which are both emulators*. This approach would have top-notch speed and wouldn't need a copy of OS X to work.)

Thoughts anyone?
(Please leave a comment...) :)

*I stand corrected (see the comments), both are virtualizers.