A Wine-like compatibility layer to run Mac OS X programs on Linux?

[Greg K Nicholson]

Is a compatibility layer (like Wine) to run Mac OS X programs on Linux 
feasible? Does one already exist?

It seems to me, the uneducated layman, that it should be *easier* to 
make a Mac compatibility layer (“Mine”?) than one for Windows since: OS 
X is Unix-like, Darwin is open source (so less reverse-engineering), and 
Cups is already shared between OS X and Linux, so... there's some common 
ground, right? On the other hand, OS X has a faster release schedule 
than Windows, and there's (arguably) much less demand.

Anyhow, it'd be cool if we could say “all OS X programs will Just Work™ 
on Ubuntu, too”.

-- 
Greg