The latest plot details reveal how this S.H.I.E.L.D. agent comes back from the dead, but be warned, there are heavy spoilers below, so read on at your own risk.
The following details have not been confirmed by Marvel or ABC at this time. It should be pointed out that Coulson was killed by the spear of Loki (Tom Hiddleston) in Marvel's The Avengers. It seems highly unlikely that the villainous Loki would be in on this ruse, so how exactly could they "fake" Agent Coulson's death? We'll have to wait and see if ABC picks up Marvel's Agents of S.H.I.E.L.D. to find out.