You can view and control the desktop of almost any OS from any OS with VNC (Virtual Network Computing):
http://www.realvnc.com.
And it's FREE! (unless indicated otherwise). You can also download the source code:
http://www.uk.research.att.com/archi.../download.html. Many people have posted their own mods of the code for virtually every platfoem (PalmOS included). You need to run the small server app on the machine(s) you want to control, and of course the clinet app on the controlling machine. Various Mac OS X versions can be found at Versiontracker. Be sure to notice if you're downloading the server AND client or just the server.
Hope this helps....Cassj