Don't find the Dock useful in Mountain Lion? Lifehacker reader Luke Carbis explains how you can conceal it with a simple Terminal script.
I've searched around for a way to permanently disable the dock in Mountain Lion: for me it just gets in the way and I can use Launchpad instead. I couldn't find a perfect option -- some hid the dock in the corner of the screen, some moved it to the top, some used third party software.
Then I remembered an article I read on Lifehacker a little while ago about making the dock appear instantly - and changed it so that it had the effect of disabling the dock.
In Terminal, use this command:
defaults write com.apple.Dock autohide-delay -float 1000 && killall Dock
This will make it so the Dock only appears after a 1000 second wait. It's still there, functioning normally, and still appears in Launchpad and Mission control (which is the way I wanted it), but it's never in the way.
I ultimately opted to use a 2 second delay instead, which makes trying to open the Dock more of a purposeful thing and prevents accidental opening!
To reset it to the defaults, just use this command:
defaults delete com.apple.Dock autohide-delay && killall Dock