Transfer OS X Dashboard Widgets Between Computers
Widgets are saved at /Library/Widgets/ and /Users/[user]/Library/Widgets/

If you copy /Users/[user]/Library/Preferences/com.apple.dashboard.plist that will copy your Dashboard configuration.

Each widget will have it's own configuration file in /Users/[user]/Library/Preferences/, for example widget-com.apple.widget.weather.plist