One thing I didn't see touched on in any of the articles above is that there is apparently a bit of a mystery attached to Coulson's resurrection that implies that it might be something more than simply dying and being revived seconds later... even though that's the story the SHIELD doctors tell to Coulson himself.
The mysterious nature of the spoiler above could imply that the early fan speculation about Coulson's survival could actually be correct and that...
Coulson didn't actually survive after all but is instead a SHIELD Life-Model Decoy
who doesn't realize what it truly is and thinks it is actually the human Coulson.
Since Tony Stark implied that the Life-Model Decoys exist in The Avengers
with his joke to avoid talking to Coulson, that would certainly be a possibility. And they're something both SHIELD and Stark have used several times in the comics.
However, there are numerous other methods of bringing back people from the dead in the Marvel Universe, so that's not the only possibility, though I'd consider it the most likely. Regardless, it seems as if it might be an important plot point later on and/or a continuing mystery throughout the season.