Both the US and UK online Apple Stores are showing the 8GB and 16GB iPhone as "Currently Unavailable."
The French and German Apple Stores continue to show stock of both models of iPhone.
It should be noted that during the last financial results announcement Apple did state that shortages may happen in the near future but blamed increased demand rather than depleting stock.
Most of this week O2 in the UK has had intermittent availability of the 16GB iPhone.