I thought C:\Qt\qtcreator-2.5.2\bin\designer is where the designer integrated into Qt Creator looks for plugins. Putting the worldtimeclock plugin in here works fine.

I am talking about two designers. The stand alone that comes with the with 4.8.2 lib installer and the one integrated into Qt 2.5.2. I can get the plugin to work in the standalone, not in the integrated.