I'm using Ubuntu 12.04 with a dual monitor setup. The Workspace is spread between the monitors in Xinerama mode, not mirror. Now, the top panel is present on both the monitors. It's simply doubled. ...
I have a dual head setup (NVidia Twinview) which makes is possible to have two windows maximized at the same time (one on each monitor). The problem is that Unity only displays the Close|Min|Max ...