  In light of recent observations of an anomalous excess of high-energy
positrons and electrons by the PAMELA and Fermi LAT experiments, we investigate
exotic cosmic-ray signatures in scenarios with unstable dark matter that decays
with an extremely long lifetime. We identify decay modes capable of explaining
the observed anomalies and mention constraints arising from measurements of
antiprotons and gamma rays. We also discuss complementary tests by measurements
of anisotropies in diffuse gamma rays which should be accessible to Fermi.
