Saddam and the unexpected hanging paradox

All this speculation over which day Saddam Hussein will be hanged upon (and the current 'breaking news' suggests this will be tomorrow) reminds me of a paradox which puzzled me as a child. The paradox goes something like this (updated to reflect the current context):

"Saddam Hussein is sentenced to death by hanging, after his appeal fails. Officials tell the media that the hanging will take place sometime in the next four weeks, but that they won't know which day it is in advance, and instead will receive a surprise briefing two hours before the execution takes place.

Journalists ponder this, and speculate that the hanging couldn't possibly take place on the last day of the four week period, as it would then no longer be a surprise, and they would know the news before the briefing took place. Similarly, they work out that it couldn't be on the second-last day either, as the final day has already been ruled out, and so it on the morning of that day they'd know that it would be the only day left on which the execution could take place. By the same reasoning, the hanging couldn't take place on any of the other days either, and so the journalists go to print with a front page headline suggesting that Saddam will be saved from the noose.

The next day, Saddam is hanged, unexpectedly after all."

Since first discovering this paradox, I've occasionally thought back to it, but have never figured out exactly how it works. Upon further reading - well, a quick search through Wikipedia anyhow - it seems that philosophers can't agree on an answer either. The article there, named the Unexpected hanging paradox, notes two responses from the epistemological and logical schools of philosophers, which I won't bother to try and summarise here. The list of paradoxes is also worth a read.

The Saddam hanging hasn't actually invoked this paradox of course, although it would have been a good opportunity to do a real life demonstration.