Plus, the floating mode isn't bad ;)
Also, if I start gnome-terminal, run tmux, and put it full-screen.. isn't it a "gnome tiling manager" ?
It took watching the video to see that it was more integrated than I first expected.
I tried to use the tiling window manager xmonad and found it excellent for terminal stuff. The problem was everything else.
Firefox/thunderbird/etc. don't work in a tiling window manager, particularly Firefox and particularly popups.
Had to hack it up a bit to show the shift key, and only the most recent keypress.
And gnome-shell-list has built in screen recording.
Still, none of those approaches solve the problem in all situations. Managing windows can be “uncomfortable”. Sure you can make use of workspaces, or tags (à la dwm, I think the tag paradigm is beautiful) or whatnot, but you don't want to think about the act of switching windows. Have you ever found yourself alt-tabbing through a pile of windows and be annoyed by not getting to the right window easily enough (“Oh, drat, I pressed Tab one too many times”). Whenever I have to use OS X, I press the Exposé shortcut for almost every context switch.
So yeah, this is kind of extension is more than welcome and others should continue to innovate. If nothing else good comes out of Gnome 3, at least it would have pushed people to think about their interaction with the interface.