Film Well, this is one way to fix the fubar in the European pressing of The Avengers.
Wow, Joss, that's well, well that's ... hmm ...
How does this effect The Avengers as a narrative? To an extent the death of Coulson's what motivates the team to assemble, though given that Fury lied about Captain America's trading cards and he's a shifty blighter anyway in many respects, it's not unlikely that he'd cover up Coulson's "death" even from the other agents for whatever reason. He's clearly supposed to be gone in the short film Item 47.
The best approach would be not explain it. At all. Just have him wander in as though nothing happened, or that's it's simply expected amongst his fellow agents that he would just turn up again. He's too cool to die. Or if it does become a story point, it is *the* story point, the whole of the potential first season pinioned around the mystery of how he can be walking around. A change in the fabric of reality or some such.
Either way, for all Joss was originally indicating that the television series would be dislocated from the film series, it seems less and less likely that there won't be some high profile cameos, especially in sweeps. Cobie Smulders' Maria Hill seems the most obvious.
You're probably going to be reading this blog post cloned across a dozen other blogs over and over again in the next couple of days written by people who're far more knowledgeable about the comics than I am (assuming you haven't already). Is Coulson a character in the comics? I have no idea.
Either way, the return of Coulson shows this isn't just some side project for Joss. He's right behind it creatively. This is good.