  It is well-known that a compact Riemannian spin manifold can be reconstructed
from its canonical spectral triple which consists of the algebra of smooth
functions, the Hilbert space of square integrable spinors and the Dirac
operator. It seems to be a folklore fact that the metric can be reconstructed
up to conformal equivalence if one replaces the Dirac operator D by sign(D). We
give a precise formulation and proof of this fact.
