Head over to the widgets page to view the available widgets.
Click on the 'Configure' button for the widget in question to open the configurator.
At the top you will see an area for reinstalling the widget on another theme. Simply choose the desired theme and hit the install button. Within this list of themes, for any theme that is 2.0 compatible you will see a (2.0 Ready) at the end of the theme name which means no code for installation is required.
If the new theme you installed the widget on isnt 2.0 ready, make sure to paste in the snippet code into you theme code outlined in the documentation item linked.
