A new Gnome Shell mockup shows how the old Gnome Shell behavior (which is actually still the current Gnome Shell behavior) and the new Overview-Layout Gnome Shell branch can work together, bringing both innovation and usability (called "Tiled view"):
(If your video does not support HTML5, you can watch the video @ YouTube - but it's lower quality)
The workspace sidebar is hidden by default, and slides out when the cursor is near the edge of the screen or when a drag is initiated on a window or launcher.
But that's not all! Jakub Steiner explains on his blog:
Now while I think the workspace thumbnailing addresses the most useful part of the tiled view, we still rely on the user to do workspace "management". So the next step is to make the Shell do the heavy lifting. Stay tuned.
What do you think?
[via Jakub Steiner]