Yes, Xwindow has had the feature for ages, mostly on Unix/Linux systems, but also on openVMS, Macs, etc.
But there are actually 2 different behaviors.
1. The basic one is that every program can actually be started to display its windows remotely.
(I wonder whether this will be possible on the Mac -- Of course, using X11 we already can do this now).
2. The higher level one is where the whole login session uses a remote screen.
And there is more to it than just making the...