Looking for a rather interesting program

[Dragoncrest]

	Friend of mine has a rather interesting setup on his machine that I would 
like to have on mine.  Apparently what it is, he has a program that allows 
the mouse and keyboard to automatically switch between two computers.  So 
as soon as the mouse moves off the screen on one, it jumps on the screen on 
another one.  The computer who has the mouse on its screen gets access to 
the keyboard.  This program is supposedly able to control up to 4 machines 
via a network using one mouse and one keyboard and even possibly one 
monitor for all four of them with an optional setting.  There's supposed to 
be programs that allow you to do this (both for linux/bsd and for windows 
should you happen to have a windows box in that mix) and I'd love to set 
those up on my machine, but I don't know what they would be and my friend 
is gone to another country for several months so I can't ask 
him.  :(  Anybody know what this setup is?  I know it's not VNC.  That much 
is obvious.  It has something to do with the desktops in xwindows...I 
think.  Not totally sure though.  Any info is more than welcome.  Thanks.