Different Launchers for Different Workspaces?

Solution 1:

It took a few years, but now you can have a launcher with diffent pinned applications in different workspaces with Unity LauncherSwitcher. (Thanks to webupd8.org for making me aware of it.)

Run these commands to install it:

sudo add-apt-repository ppa:vlijm/lswitcher
sudo apt-get update
sudo apt-get install lswitcher

Solution 2:

Unity does not have 4 launchers so you can not have different launchers for different viewports (yes I used viewports, not workspaces).

Unity Workspaces Switcher uses Compiz version of viewports so basically you have a launcher that activates a split screen based on the vertical and horizontal amount of viewports. This is not the same as workspaces in Gnome 2. This is actually 1 workspace with 1,2,4 or more viewports.