So, Ahmadinezhad has said he wants to get rid of Israel. And many preoccupy themselves with how, practically, Iran could accomplish it. Launching a nuke at Israel is considered so impossible that it is dismissed. (Then again, hijacking civilian passenger airplanes and crashing them into buildings was similarly dismissed.)
But Iran doesn’t have to launch a missile. All it has to do is give a nuke to Hezbollah, who is across the border from Israel.
Ever heard of a dirty bomb? Iran could be the first one to use it, through Hezbollah.