Since I upgraded to the new Ubuntu 12.04, I have been getting the old gnome style Alt-tab switcher instead of the new one. Is there any package that I need to install for the same? I am using Unity-2d. Please help.
Unity-2D has always been using the old style application switcher. Only Unity has the newly styled application switcher. The behaviour you are currently experiencing is intended and is not a bug. So, you don't need to fret too much about it.