  Gravitational divergences associated with singlet fields in supersymmetric
theories are reexamined, and their possible contributions to the low-energy
effective theory are pointed out. We demonstrate that such divergences are not
necessarily harmful and that Planck-scale physics could play an important role
in models of low-energy supersymmetry breaking via a radiatively induced
tadpole term in the scalar potential. In this case, gravitational divergences
play the role of the supersymmetry breaking mediator, leading to a simple
realization of the so-called messenger model. We also point out a new mechanism
for the generation of mass terms for the Higgs fields in models of low-energy
supersymmetry breaking, as well as a horizontal messenger mechanism in which
the horizontally charged scalars are rendered heavy. Implications to the flavor
problem in supersymmetric models are also discussed.
