It probably means he's using http://synergy2.sourceforge.net/ - I've used it for similar things (typing on a Mac laptop, with a second monitor hooked up to a Linux desktop) and it's a brilliant solution.
Me too, but Synergy finally convinced me that it's possible to build amazingly good software that lasts.
* Make it peer to peer instead of client/server, keyboard & mouse events from all peers are shared, not just the server's
* Use mDNS (e.g. Bonjour) to auto-detect nearby peers and auto-connect to known ones. Also, use some kind of authentication - you don't want random people on a public wifi to be able to get access to your clipboard because you forgot to quit your synergy client.
Alas, I haven't had the time. Maybe this summer...
I'm trying to decide between 2x30" and 30" + 2x20"(in landscape) on either side.