Gnome Shell has fairly decent support for multiple monitors. My particular setup has two monitors side by side (probably the most common configuration), but one monitor sits directly in front of me while the second is off to the side. By default, the monitor on the left side had the ‘panel’ at the top, and activating the Activities view would display workspaces and applications there as well. 
In order to change this, start the Displays application (System Settings > Displays) . Notice that there is a black bar at the top of one of your monitors; this bar represents the ‘primary’ display. You can click this bar and drag it to whichever monitor you would like to make your primary display. Mac OS X works in a very similar manner, so you may be familiar with that operation as well. Another feature that I found interesting is that the primary display is the only one that has workspaces. In other words, any windows you place on the secondary monitor will stay there when you switch workspaces, while the primary display will switch. This one is also configurable, but not as easy. For GNOME Shell 3.2, fire up gconf-editorand navigate to:
/desktop/gnome/shell/windows
There is a key in this folder appropriately named:
workspaces_only_on_primary
Uncheck this box to change the behavior so workspaces are universal. After you make this change you will need to restart Gnome Shell (ALT+F2, enter ‘r’ without quotes and press enter).
For GNOME Shell 3.4, fire up dconf-editor and navigate to org.gnome.shell.overrides and uncheck workspaces-only-on-primary.
This sounds like exactly what I need! Thanks!
Thanks! very useful tip. I was searching for how to switch primary monitor.
This options suddenly stopped working for me on ubuntu using the ricotz ppa. Any suggestions?
I’m not 100% familiar with that, being mainly a Fedora user, but it seems that’s for gnome-shell-testing. As with anything in a sort of -testing type environment, certain things are bound to be broken at any given moment in time.
Perhaps wait a bit, then do your updates and see if it is fixed. If not, you may want to hunt down and file a bug at the appropriate bugtracker for that PPA.
For some reason on F16 today this only worked for me when I modified this setting instead:
/desktop/gnome/shell/windows/workspaces_only_on_primary
Notice windows is plural instead of just window singular.
FWIW you can set this on the command line too ( I have a setup script that I use to configure newly installed systems)
$ gconftool-2 –set /desktop/gnome/shell/windows/workspaces_only_on_primary –type bool 0
$ gconftool-2 –get /desktop/gnome/shell/windows/workspaces_only_on_primary
false
I’ll update the article, as this does seem to be the case. Nice find!
Ubuntu 12.04 / Gnome Shell 3.4 is different again; use dconf-editor and navigate to org.gnome.shell.overrides and uncheck workspaces-only-on-primary
Updated the article to include the differences between them. Also added in a nifty picture of the gconf-editor location.
Thank you! Almost a year after you wrote this… it still helped me out.
Thanks! very useful tip.