I am trying to install your plug in to C:\GIMP 2\lib\gimp\2.0\plug-ins on Gimp 2.8.6 on Windows7. I do not see it registered in the plugin browser (was looking for it in "/Layer/M_ove To") . If there is any debugging information I can provide tell me.
FYI. I am a Java programmer so if you need to get technical feel free :)
Put *.scm files in $HOME/.gimp-2.8/scripts and not plug-ins. I was led astray by my previous experience of putting a .py file in the plug-ins directory. To others reading the site http://www.mahvin.com/2009/09/gimp-how-to-install-scripts-plug-ins-to.html helped.