  A formulation of Einstein gravity, analogous to that for gauge theory arising
from the Chalmers-Siegel action, leads to a perturbation theory about an
asymmetric weak coupling limit that treats positive and negative helicities
differently. We find power counting rules for amplitudes that suggest the
theory could find a natural interpretation in terms of a twistor-string theory
for gravity with amplitudes supported on holomorphic curves in twistor space.
