One thing I can tell you is that Israel will not wait for the worlds' approval if they feel that Iran is about to go "Hot"
It is obviously a very different scenario than was Osirik, Iraq in 1981.
For starters, Iran's facilities are spread out, and deep underground.
For another, more enemy territory would need to be overflown, with it's inherent risks. (In 1981, The IAF made this work for them by having pilots that spoke perfect Arabic, in perfect dialect).
An attack on Iran would require in-air re-fueling, or possibly a secret agreement with a country such as Turkey for the use of their airfields.
Remember Turkey has strong military ties to Israel, and definately does not want a nuclear Iran. Still, this may be too much to expect, what with the very fine line that they staddle with their Muslim population.
Another wild card is who will be PM at the time. In 1981, with Menachem Begin at the reins, Israel would do whatever neccessary for it's survival, and the hell with world opinion. I'm not so sure the current Weasel, er, Prime Minister, Ehud Olmert has the intestinal or moral fiber to make that decision. At that point I go back to my opening statement, and believe that in a worst case scenario, even he would be "made to understand" that he has no other option.
I hear people say things like" hey, if it's okay for Israel to have nukes, why can't Iran, or anybody else also have nukes".
The easy answer is that Israel has had those nukes for close to 40 years, and has never threatened a single nation with them. They are a deterrent, much as with the other Democracy's around the world who possess nuclear weapons.
However, as was the case with Iraq in the 70's and 80's, Iran has made it very clear what it's intentions are, and I have no doubt that there would be a surplus of pilots ready and willing to volunteer for this mission, even were it to be very clear that there would be no return Home