If you need to gain some more space on your Ubuntu desktop, you can use the auto hide feature of Panel. By enabling auto hide, your panel is hidden and it only becomes visible when you hover your mouse cursor over it. You can achieve this in two ways in Ubuntu Linux. Let me explain both:
In your Ubuntu desktop, Press Alt+F2. It will open a dialogue box.
Enter gconf-editor in the text box and click Run. This will load the Configuration Editor.
Now select Apps > Panel > top level > top panel screen0 from the left sidebar. It will then display properties of Panel(Taskbar) in next window. By default, auto_hide property is unchecked, checking it will auto hide the taskbar.
Second method is pretty easy. Right click anywhere in Panel and select Properties.
Click Autohide option and press Close.
Your panel will be hidden now. Enjoy!