Hitchens finds it in France and explains:

And that reason, uncomfortable as it may be, is that most of the Communist electorate defected straight to the National Front.

To which I would add they they are equally happy to turn back to the left if the right fails to deliver on the grievances of the former 'Communists'. That is what I would term the Dutch lesson: dissatisfied voters looking for a new and decisive direction, irrespective of ideology. And yes, that is the hallmark of uncertainty:

Add to this the rather peculiar fact that a huge tranche of voters—most recently as large as 40 percent—simply refuse to tell the opinion polls (who last time got everything calamitously wrong) how they intend to cast their ballots. Again, the best intuitive explanation of this reticence is that many people are embarrassed to declare a Le Pen allegiance in advance.

Not sure if Hitchens is correct here as it would seem that a high level of uncertainty is an increasing characteristic of voting trends in Western Europe. And, the number of 40% that is apparently undecided again is in sync with Dutch trends where a similarly large floating vote was measured shortly before election day.

UPDATE: And like the Dutch, the French are increasingly likely to pack up and go:

According to a 2005 TNS Sofres poll, 2.2 million French people live in foreign countries — mainly in Europe. Half of those leaving are under the age of 35 years old, believing they will have more chance in other countries. Those departing, and above 35 years old, either say they are leaving for tax reasons or either for professionnal reasons. Even more striking; more than 90% of emigrants are pleased with their new life-styles, and 40% are planning on either never come back to live in France, or come back once they retire.

Interesting parallel.