Here is a guide that shows you how to change the opacity from the top and launcher panel and how to disable blurry dash menu on Ubuntu 11.10. You can change the panel opacity using the Ubuntu Unity Plugin in the CompizConfig Settings Manager (ccsm). To use the Ubuntu Unity Plugin you need to have the CompizConfig Settings Manager installed.
To install the CompizConfig Settings Manager open a terminal window (press Ctrl+Alt+T) and copy+paste the following line:
sudo apt-get install compizconfig-settings-manager
When installed close the terminal window and to start the CompizConfig Settings Manager press the SuperKey and type: ccsm
In the left menu click on Desktop and click on the Ubuntu Unity Plugin. Select the Experimental tab and change the value of the Panel Opacity. And to change the launcher panel opacity change the value of the Launcher Opacity. To disable the blurry background in the dash menu click on Dash Blur and select No Blur. When done you can close the CompizConfig Settings Manager.