In the past I have already addressed this issue by publishing guides on how to make a desktop based on KDE but VERY VERY similar to Mac-OS X.
Of course required to carry out various operations and take care of the various aspects individually.
Today I propose instead a complete package: Phoenix: Mac4Lin ver.1.0 Released! .
Unfortunately it is only available for the GNOME desktop, like Ubuntu for example, while not function on KDE desktop, such as Ubuntu.
The most interesting aspect is that this package not only deals with changing the desktop and windows to resume the style of the apple, but also various external programs such as Firefox, Thunderbird, and Rhythmbox.
The result is quite good: