As @jrg mentioned, this is still possible as Unity (Unity 3D, not the low-power 2D version) is largely built using Compiz.

You'll need to install the Compiz Config Settings Manager Yourself though. Precise steps are:-

1. Install CompizConfig Settings Manager using apt-get install compizconfig-settings-manager compiz-plugins-extra.


2. Run it (just type Compiz in the dash and you'll see it).


3. Click Window Management.


4. Enable the Put plug-in (select the check-box).


5. Click on Put.


6. Configure the shortcut for Put to next Output (click the pencil icon next to the keyboard shortcut for Put to next Output.


7. Logout and login again for the changes to take effect (from the comments!)