ON THE ENDING OF THE PRESTIGE BY CHRISTOPHER PRIEST

An explanation of the ending of The Prestige (the book) below the fold. Spoilers, obviously.

First of all, the man in the vault is Rupert Angier. To be precise, he is the reunion of the "spectral" Angier with the corpse of the "corporal" Angier, as the former describes at the end of Part Four. This is shown by the fact that the handwriting on the label of Nicky's prestige is Angier's.

Second, and more importantly, the prestiges in the vault are not dead, but, in Andrew Westley's words, "frozen in life, made inert without being made dead" (from Part Five, section 4). That Nicky's prestige can communicate with Andrews means that Nicky's mind is still inside, and presumably the same is true of Angier's prestiges.

I've seen complaints that Angier's section overshadows Borden's, but the ending makes it clear that this is intentional: Angier is the principal protagonist, and Borden the secondary protagonist.