This is a video of the Shahab 3 Iranian medium-range ballistic missile (MRBM) with an estimated maximum range of 1,200 miles. Its one of several videos on test firings of the missile, and tends to be a good one from CNN as it shows a map of the region with nations the missile could be targeted at. Shahab 3-B to D versions of the missile also exist with potentially greater ranges and enhanced abilities to evade air defense systems, even in the terminal phase for the warhead itself.
The missile can carry one 2,200 pound warhead or five smaller warheads of about 620 pounds each.
The New York Times recently ran a lengthy article over the ongoing debate about bombing Iranian nuclear facilities, that involves interviews with military and political leaders in Israel: http://www.nytimes.com/2012/01/29/magazine/will-israel-attack-iran.html?_r=1&pagewanted=all
The article ran on January 25th, 2012 and stated that Iranian scientists estimate (once given the order by their government to do so) that it would take them 15 months to create a nuclear weapon compact enough that it could be fitted to the Shahab 3 as a warhead.
US and Israel strategies to counter the development of Iranian nuclear weapons capacity often focus around the possible use of "bunker buster" bombs to destroy such facilities. (This assumes of course that the location of all Iran's major facilities is known to western intelligence and that Iran doesn't currently have, or cannot obtain smuggled enriched uranium or plutonium for the assembly of missile-based warheads before or after bombing raids are conducted). I'm reminded of those stories of Russian weapons grade material in storage facilities guarded by one night watchmen and a chain link fence with a rusted padlock on it... With so many Islamic states bordering south-western Russia, how hard would it be for Iran to smuggle material through them?
Probably the best weapons system that may be able to penetrate the Iranian nuclear research structures is the US built Massive Ordnance Penetrator (MOP). It weighs 30,000 - 37,000 pounds with a 5,300 pound explosive. It is so heavy that it can only be effectively carried by the B-52 bomber or B-2 (Stealth) bombers. The US is known to currently have 16 MOPs in inventory and the existing fleet of 20 B-2s have been refitted so they can carry them.
Each B-2 costs approximately $1.4 billion dollars to build and each MOP bomb costs about $340 million dollars per this video. 20 MOPs have been ordered but no further B-2s are under construction.
The MOP can penetrate 200 feet of concrete reinforced to handle 5,000 pounds per square inch of pressure or about 130 feet of rock. Is this enough to seriously damage Iranian facilities? The Iranian facility at Qoms that is enriching uranium to a 20% level (which is much higher than is needed for nuclear fuel for power plants, which is lower than 5%) is said to be buried under over 200 feet of rock.
Israel also has its own bunker buster bomb inventory and about 350 F-16 and F-15 fighter aircraft to deliver them. There are estimated to be at least a dozen sites that such an engagement would target. Currently Israel has 100 GBU-28 bombs in its inventory which are 5,000 pound laser guided bombs with an explosive that weighs 630 pounds and can pentrate over 20 feet of reinforced concrete. There is also a push to sell Israel 200 GBU-31 bombs from US inventory(http://www.bloomberg.com/news/2012-02-01/u-s-should-give-israel-bunker-buster-bombs-policy-group-says.html), which are smaller by comparison to the GBU-28, being either 1,000 pounds or 2,000 pounds for the GBU-31B, but are precision guided bombs that don't require laser targeting in good weather to be precision munitions: http://www.designation-systems.net/dusrm/app5/jdam.html The GBU bombs also have the advantage that they are small enough to be carried by fighter aircraft: Test Launch of a GBU-31B
Of course there are all sorts of ways an attack could go wrong. Iran has state of the art air defenses around its sensitive facilities, and some estimates say Israel would only get one chance to bomb the sites due to limited refueling capacity for its fighter fleet. Analysts have estimated a concerted series of attacks over several weeks with up to 1,000 bombing runs might be necessarry to effectively set back Iran's ambitions more than a few years. The US military is in the process of upgrading the MOP for such potential action however, and there is always the prospect of an attack being a joint US/Israeli one as well. Israel's aircraft would have to overfly Iraq to get to Iran as well, which would require at least tacit support from US military assets in the region that would need to look the other way when such an attack was launched.
Iran would survive such an attack, and would be even more driven to develop a nuclear weapons capacity afterwards. The international community has not been able to stop North Korea from getting nuclear weapons, and its people have been on the verge of mass starvation for decades.
Other regional powers would also go nuclear. Aside from Turkey, Egypt and the gulf Arab states, Saudi Arabia has known plans to acquire nuclear weapons from Pakistan "the next day" should Iran go nuclear: Saudi Nuclear Agreement with Pakistan
2012 may very well be the year where we see some of these weapons systems used. If the analysts are right, there is probably only about a year's time left before Iran inevitably becomes a nuclear weapons power.
