All the credit for this post should go to John Stegeman for providing the solution. I will just copy the main points here, so I can find it more easily.
The story goes like this. People are seeing different date and time formats after deploying and running their applications on an Oracle IAS rather than their embedded OC4J where the dates and times display correctly.
The solution appears to be the addition of a
<locale-config> tag inside the faces-config.xml file.
The entire thread that explains everything can be accessed from here. Furthermore John also posted a link with all the two letter ISO country codes which is available from http://www.bcpl.net/~j1m5path/isocodes-table.html
One final remark. I have been deploying applications on Oracle IAS running on Linux (SuSE Linux 8 and SLES9), since version 9i and never run into anything like it. Could that be a Windows issue ? :-)