That's an interesting theory, although i'm not sure that it makes sense, as it would suggest that the creators are playing with us, and that what we've seen since that episode, isn't actually real.
I mean if she died in the explosion, then how would she still be 'here'? Although i guess the fact that the deceased Christian Shepherd can physically interact with living things (i.e. Aaron) may support this theory, in that if he can..perhaps Claire (who is dead under this premise) also can. I guess it could work on this level. Although I think it would be a bit of a forced entry, since it would seem a bit of a 'sudden' plot-line to force on us at this juncture.
I have always been facinated with the role of the 'dead' in Lost..but I think that the evidence points to them being able to exist on the 'other side' as 'spirits'..and not being able to be dead, yet also physically exist amongst the 'living'.
I also don't think that Ben, Locke (etc) would be able to interact with her for so long after the explosion without her 'phasing over' or disappearing, if she was already dead. Had the explosion been an electromagnetic one, then maybe, cos that stuff causing all kinds of crazy stuff to happen. but this was a standard explosion..
Still, an interesting theory.
Personally my understanding of the Miles thing, is that he can 'sense' Claire's 'impending' death..
I guess it's a fine line between
psychic and
medium.