Indeed, unless the UN Security Council figures out what to do to prevent Iran from acquiring nuclear weapons -- and it doesn't appear that they have a clue or the will -- Israel may feel that they have no other recourse but to act unilaterally. This would likely take the form of strategical bombing raids -- a troublesome turn of events that would make an already unstable region even more volatile.
And Israel is not alone in the Middle East. There are other concerned nations in the region who are wary of Iran's rise to nuclear status, including the potentially strange bedfellows of Saudi Arabia and other Sunni Arab countries. Iran, along with her allies like Syria, Hizbullah and Hamas, would surely make the Middle East a miserable place in the event that Israel makes a preemptive strike.
There are, quite unfortunately, a number of factors that may compel Israel to do so:
Some commentators have even speculated that Israel may attack in the coming months before the Obama administration is sworn in. The advantage of doing so would be to get quick U.S. support, to acquire needed arms and gain other tactical advantages.
the popular sentiment in Israel today is "stop the appeasement!" and it has transcended political divides; defense Minister Ehud Barak has been quoted as saying that a life-and-death military confrontation is a real possibility it's election time in Israel, which could see the introduction of a more hawkish administration the Israeli air force is likely very capable of such a mission; the destruction of a Syrian nuclear facility in 2007 and the lack of any international reaction to it may be interpreted as an example for the coming action against Iran diplomatic initiatives and UN sanctions are seen by the Israelis as hopelessly ineffective; this is particularly troubling because it appears that president-elect Obama may support such measures
My own opinion is that such an attack would be premature. Analysts have predicted that Iran will be nuclear capable sometime between 2010 and 2015 giving Israel some time to feel out the Obama administration.
That said, we should not understate the gravity of Israel's situation. They have been threatened with annihilation time and time again by the current Iranian regime. And in high-stakes situations like this, perception is everything. The Jews are, for very understandable reasons, very sensitive to such threats. As John McCain said during one of the presidential debates, this is an "existential threat" as far as Israel is concerned.
Desperate times may call for desperate measures.