I can't get this to work in CS5. I made the edits at the start of the script:
if ( app.name == "bridge" && app.version == '4' )
And the script doesn't cause any error when I launch Bridge, but there's no EM2 panel. For files where I have EM2 metadata, I can see the metadata in the 'Raw Data' panel and can see the 'Mediapro' and 'Expressionmedia' schemas in the 'Advanced' panel.
Oh, I'm on Windows XP SP3 and Bridge 18.104.22.168