Hi Phil,
its been very interessting. Problem appears to be caused by Bridge (1.4.0.6 WIN). I had processed the whole workflow we have. After entering the IPTC Information and saving, the information are no longer shown in CS3. This sounds more like a Bridge bug.

But I couldn't repeat this on Bridge CS3. There it adds Subject field correctly to make sure information are shown in PS CS3.

Thanks anyway for the hint with IPTCDigest.
-cheers
b3nton