The 21st April does not have any great significance in these parts, but it certainly does on the other side of the Channel, as on that day in 2002 (Yes, I had to look it up) the French Socialist Party's candidate Lionel Jospin failed to make it past the first round and into the run-off, resulting in a Chirac / Le Pen decider. Which Chirac won by a landslide, traumatising much of the French left as they turned out en masse to vote for him rather than see a Front National president. Still, they should not have voted for various Trots and other no-hopers thinking it was cost free, should they?
Anyway, it is by no means certain that Sarkozy will run again and current polling suggests that it is only Sarkozy who could out poll Marine Le Pen in round one and thus face Dominique Strauss Kahn (likely PS candidate in 2012) in the knock out. François Fillon would tie with MLP and both Jean-François Copé and Jean-Louis Borloo would be out of the hunt after the first stage.
Marine Le Pen is rather more subtle in her public statements than papa, but she is some way off being what I would deem a respectable voting option.