X windows and especially KDE/Gnome are in some sense an implementation of a various set of APIs (application programmer interfaces) that allow programs to call certain functions and get certain things to appear on the screen, behave in certain manners, pass signals around, etc.
Aqua has totally different APIs. A compiled KDE program isn't going to run under Aqua any more than code written for a windows machine would run if compiled in a mac environment. Code that just accesses the CLI is usually far more portable because there is a much smaller set of assumptions to make about the system. That's why its no problem to recompile Lynx for the terminal, but people have been spending a lot more time getting a GIU implementation of say, renice.
Now, Tenon has made a program called Xtools that allows X windows programs to run in aqua and have the aqua look and feel. This was no small effort, and while you can download a trial version, the full verison will cost around $400. And Xtools doesn't have KDE/Gnome installed, so you'd have to rigure out how to compile them for the mac, and then install them under Xtools' implementation of X windows. Heh.
Also, some folk have installed Xfree86 on their OSX boxes, and run an X session offscreen (display:1 or something) and then using a VNC server running under the X session, send the screen to the OSX display, where they are running a VNC client. Confused yet?
VNC (virtual network computing) is a free utility that allows you to control obne computer from another over a network. Except that someone has managed to use it to control a differnt windows system (Xfree86) running behind the scenes on their OSX box. I wish I could remember the link about this... the server binary can be found at
http://www.uk.research.att.com/vnc
or on stepwise.
Again, as far as KDE and Gnome go, I think you're on your own.
The final option is to just install Xfree86 in the CLI, and then each time you want to use X windows programs, you just have to log out and log in as >console, and then you can start up an X session.
http://mrcla.com/XonX/
deals with this.
Hope this helps a little,
zach
