I'm still hoping to see Iron Man this weekend, but it looks as though Spencer Ackerman has already nailed all there is to say about it:
The second way Marvel subtly readjusted Iron Man for America's post-Vietnam sensibilities was to reveal that the reason Stark could control neither his company nor his relationships was that he couldn't control himself. Stark's booze-soaked, womanizing lifestyle was cleverly reinterpreted as rampant alcoholism and self-loathing. His drive to save the world was nothing more than a martyr complex born of a callow solipsism. It was a brilliant maneuver by the writers. Iron Man began to ask America: Would you trust such unfettered, unaccountable power to someone this messed up? The introduction of War Machine took the critique a step further, showing that the very act of donning the armor makes you messed up. Some exercises of power are too dangerous to be left in the hands of one man. The writers never turned Iron Man into a villain -- that would have been the easy way out. Instead they presented a fascinating character study, a compelling Cold War critique, a subtle plea for liberal internationalism, and a defense of a series of theses presented to the world in America's founding documents. It helps that Iron Man also blows stuff up.
Other recent updates to the Stark/Iron Man story have jettisoned the Cold War element but deepened the dynamic established in the 1970s. In Extremis, a reboot of the franchise during the current Bush era, Warren Ellis, one of the most talented comic-book writers currently working, has Stark unable to answer the question "What is the Iron Man armor for, Tony?" A left-wing filmmaker, dismissive of Stark's protestations that he's more than a weapons merchant, asks, "Do you think they have your painkilling drug pumps in Iraq? Do you think an Afghan kid with his arms blown off by a landmine is remotely impressed by an Iron Man suit?" Tony Stark is meant to be read as a tragic figure. He is one of the smartest men alive, yet he cannot think his way out of the traps his genius constructs for him. And so he blunders, again and again, into a hell of unintended consequences.