Recently I have updated my project dedicated to show how to implement Alfresco Java-Backed WebScripts. All the examples are related to the official Alfresco Wiki.
Now this project supports all the versions of Alfresco, I have created a new branch dedicated to all the versions until 4.1. The main trunk allows to build your AMP for all the versions of Alfresco starting from 4.2. This is done thanks to the latest version of the Maven Alfresco SDK.
I also added the MoveCategory example as described in the article written by Jeff Potts.
This means that now you can download two versions of the AMP module depending on your Alfresco version.
For more information visit the project website.
If you have issues during the use of this module, please raise an issue.
Hope this helps ;)