Is it possible to reassign the "Pinch with thumb and three fingers" gesture to activate Dashboard instead of Launchpad? I don't really have a use for Launchpad, but the gesture to me makes sense for Dashboard. I experimented a little with BetterTouchTool, but it doesn't have the gesture available, and I'm not sure it would work well with the sequence of successive pinches and spreads to go from desktop Expose to overlay (normally Launchpad).

Ideally I'd like to see if there's a plist tweak that can be made somewhere that would keep the gesture behavior exactly the same, but substitute Dashboard for Launchpad.
I'm not sure if there's a plist modification you can do to alter the behaviour, but I do know that BetterTouchTool will let you replace the pinch zoom in/out gestures with custom actions. You can assign them to activate Dashboard instead of LaunchPad if you like or any number of other things. It can be a bit involved to set up, but it is very powerful in what it lets you override from the OS X defaults.

TUAW has an article on customizing a Magic TrackPad using Better Touch Tool that demystifies it a bit.