  We study the local flux of electrons and positrons from annihilating Dark
Matter (DM), and investigate how its spectrum depends on the choice of DM model
and inhomogeneities in the DM distribution. Below a cutoff energy, the flux is
expected to have a universal power-law form with an index n ~ -2. The cutoff
energy and the behavior of the flux near the cutoff is model dependent. The
dependence on the DM host halo profile may be significant at energies E < 100
GeV and leads to softening of the flux, n < -2. There may be additional
features at high energies due to the presence of local clumps of DM, especially
for models in which the Sommerfeld effect boosts subhalo luminosities. In
general, the flux from a nearby clump gives rise to a harder spectrum of
electrons and positrons, with an index n > -2. Using the Via Lactea II
simulation, we estimate the probability of such subhalo effects in a generic
Sommerfeld-enhanced model to be at least 4%, and possibly as high as 15% if
subhalos below the simulation's resolution limit are accounted for. We discuss
the consequences of these results for the interpretation of the ATIC, PAMELA,
HESS, and Fermi data, as well as for future experiments.
