I have only two computers that I use and already I miss the features Benjamin Otte describes in his recent blog post. Fortunately there is some work being done for this already! I noticed that Conduit has GConf module. I haven’t tried it so I don’t know how well it works but it’s a set to the right direction. For applications I’m not aware of any solutions, but for regular files there already some services available like Dropbox and Ubuntu One. Wouldn’t it just be a matter of bringing these all together under easy configuration system and automatic background synchronization?
I would like see GNOME go to that direction as it shouldn’t interfere with single computer use model GNOME has today. You could just decide to use it if you want.