Unusual events like the Colorado shooting bring out the stupid in people. A good example is this Schneier link to a horrible article on Slate that attempts to refute gun advocates by pointing out the shooter had body armor.
Except the shooter didn't have any significant body armor. He had a combat vest whose purpose is to hold extra magazines. I can't find a single source confirming that he was wearing metal plates that would've stopped a bullet.
Refuting this nonsense is what Wikipedia is for. It says (as of 2012-08-01): "He was dressed in black and wore a gas mask, a load-bearing vest, a ballistic helmet, bullet-resistant leggings, a throat protector, a groin protector and tactical gloves". A bullet-proof vest isn't in the list, and none of the other items would've stopped a bullet either. At most, they might provide some protection against a knife if the theater goers had mobbed the shooter.
Moreover, as the Wikipedia article on bullet-proof vests, they aren't really bullet-proof. They are resistant to bullets and help improve survivability. They don't allow you to continue firing into a theatre while getting hit by bullets from victims firing back. Getting shot by a .45 calibre stops whatever you are doing, regardless of the armor you are wearing (Update: or maybe not, see comment below).
I'm not trying to argue gun control in this post, I'm trying to promote Wikipedia. When unusual things happen, information is sketchy, so people twist the information to fit whatever they want. In our industry, this could be power blackouts, Chinese hackers, undersea cable cuts, and so on.
Whenever the argument is too perfect, and the evidence they cite fits too well, it's time to check Wikipedia. They are probably making it up, as William Saletan did in his Slate piece claiming the guy had SWAT gear. Even if you agree with the conclusion, double check on Wikipedia before repeating it to avoid sounding like an idiot.
As for the underlying argument of "gun control", I saw this Batman movie with three people who were armed (and not because of the violence the night before, but because they are always armed). Two are well trained, and would've calmly taken aim and shot the shooter. The third would've gotten excited and shot his own foot off. I don't mean this as an argument for/against gun control, but only as a piece of information.