I use the latest verison of Adobe Reader (X) and the Babylon plug-in don't work.
The "BabylonRPI" file is in this directory, but dont work:
C:\Program Files (x86)\Adobe\Reader 10.0\Reader\plug_ins\Babylon
Babylon plug-in doesnt listed in the "About Aobe Plug-Ins" menü in the reader UI
In the preferences of reader; uncheck the "Use only certified plug-ins" doesnt help.