Eugene,

Your characterization of the Iranian president's comments is not entirely accurate.  He did publicly qualify his statement to indicate that he expected Israel to collapse under its own demographics and that "wiping it from the map" meant in somewhat colorful language that it might cease to exist under that name, not be nuked to oblivion.

Just because he said as such doesn't make it so, but I do think its important to look at his body of statements.

There's also a third (albeit hard to swallow option).  That is that Iran does acquire nuclear warheads and keeps them as a deterrent rather than an active armament against Israel.  My emotions say otherwise, but my head tells me that this is what they are aiming for.