Yeah, the Iraqis flew their jets with seemingly no regard to that tone indicating a radar lock in their headsets. I recall the images on CNN of night time air strikes and you could see streams of tracers being sprayed randomly across the sky. What were those gunners shooting at.
Gun defenses are useful against very low, slow fliers, typically helos. You guys are funny, the US isn't about to attack Iran. No way. There would be too much commotion if the US attacks Iran. Israel is another story. Israel has more than enough combat cabability ( you guys seem to ignor what 75 F-15's and over 100 F-16's could do, that is a very heavy strike package, and importantly Iran will never see it coming ) to badly degrade Iran's nuclear ambitions. And who would blame them after all the garbage to come out of the Iranian President's mouth? Besides that, what would be the ramifications? While the US would be labeled the bully and all that, pretty much every nation out there except maybe Syria would silently nod their heads in assent. I can almost guarantee you the Germans, Brits and French will be feeding Israel intel ( anyone ever ask why the French workers at that Iraqi reactor suddenly held an emergency meeting away from the job site conveniently at the exact same time the Israeli's hit that reactor? Coincidence? ) right up to the moment of the strike.
Europe and a lot of Sunni regimes in the Middle East are also threatend by a nuclear Iran. For politcal reasons they cannot be seen to cheerlead such an attack, and they cannot be seen condoning more US military action in the region, but should Israel do the deed, there will be the usual noise on the Arab street and a lot of silent high-fives behind the palace walls in those Sunni dictatorships, and in the government offices of much of Europe. What is worst thing that could happen to Israel after such an attack? Israel's enemies are already constrained by the sure knowledge that the Israeli Army and Air Force can defeat any nation that border's her. Iran cannot mount a counter strike unless it uses ballistic missiles. Israal in this case is far better situated to do what the US cannot, and when diplomacy is viewed in Israel as having failed, or Iran crosses some threshold the Israeli government has set in it's deliberations ( we won't necessarily be privy to this ) they will act.