While it's easy to use the filter in Dash in Ubuntu 12.10 to show only the installed programs (and not offer suggestions), I'd like to make this permanent. As it stands, you have to reset it each time you boot your machine.
You will need to install dconf-tools, then launch and use Dconf-editor for making the change permanent
Once dconf-editor is open, use the left panel to navigate to
By removing the tick from
display-available-apps the applications from Software Center will be no longer displayed in the dash.
If you want to show them again, you will have to these steps again and put the tick back. In other words ,you will not be able to enable the Suggestions again by just using the Filter of the dash.