Just watched the video (link at Post 695) and am even more disturbed about this incident. A couple things really struck me.
First, I watched all 21 leaders arrive and enter the building. In none of those arrivals, except Bush, did Chilean guards attempt to block the doorway. As soon as Bush and wife had entered, Chilean guards immediately sealed off the doorway as if expecting something to happen.
Second, once Bush and wife were in, the Chilean president had them linger at the doorway area much longer than any of the other leaders lingered, as if waiting for something to happen.
This whole thing spooks me. I feel nervous about Bush's safety in the US, let alone on foreign soil. As a law student in Seattle, I can tell you that some of the things I hear from students and law professors alike is chilling.
One humorous note in watching the video (again Post 695) is that the incident caused a bit of a delay of the motorcades that came after Bush. For some reason, I liked seeing Vladimir Putin's motorcade at a dead standstill in the middle of the road, while Bush's SS straightened things out.
The other thing you noticed is that the other leaders entered the main door with their spouses only, not with a security detail in tow.
That is all that happened here. The Secret Svc. didn't follow the established protocol. Only the leaders were to enter through the main door. Other agents were surely inside already to receive the President.