You will find that the Weight Copy script that many of us have been using with our clothes building doesn’t work in Blender 2.66a. (Some say it does. I’m not sure.) Gaia Clary is not going to be updating the script for newer Blender versions. She doesn’t need to. Blender now has the ‘copy’ function built in.
This new feature is only visible when you are in Weight Paint mode. The picture shows the Weight Paint Tools panel open. The eighth position is Transfer Weights (and that links to a short tutorial). This takes the place of Gaia’s script.
This new feature gives us way more control than Gaia’s script did. But the selection order for transfers is the same. Select the SOURCE first and the TARGET second.
You may notice some additional tools there too; Blend, Limit Total, Fix Deforms, and Weight Gradient. Look at Blender.org’s documents page: Weight Paint Mode. There you’ll find explanations of the tools and how they work.