When I upgraded to Ubuntu 11.10 the menu bar started showing up again, even setting the “Show menu bar” on the “View” tab to false. Moreover, even calling the gnome-terminal with the –hide-menubar param, it started with the annoying menubar. I found the solution on a blog post:
sudo apt-get remove appmenu-gtk3 appmenu-gtk appmenu-qt
gnome-terminal --hide-menubar