SUNSHINE Myth?: Space Survival Without Spacesuits?

Slate's Explainer tackles a science/science fiction question that's surely been nagging anyone who's seen SUNSHINE:
Can an astronaut survive for even a few moments outside of a spacecraft without wearing a spacesuit? Without giving away too much of the plot, there's a tense sequence in SUNSHINE, the new thriller from Danny Boyle, in which three crew members of a solar-bound craft end up outside of the ship with only one pressurized suit among them.
There's a similarly horrific moment in EVENT HORIZON: the space rescue team's youngest member, under the influence of a ghostly force, wanders into an airlock, seals himself in. And as his frantic crewmates race to save him from outside the ship, he opens the airlock.
Can't trust those airlocks, can you?
The unsecured airlock in a sci fi movie is analogous to the French patio doors of slasher movies: highly freakin' permeable. The devil can just walk right in without knocking.