To quote from that web page, "The aim of OroborOSX is to make X11 windows look, and ultimately behave, as closely as possible to 'native' OS X windows." It's a very small application that's easy to install. It requires XDarwin and XFree86.
I'm using the latest version, 0.75 alpha 2 and am enjoying it much more than any other X window manager that I've tried. Take a look.

