  Indirect detection of particle dark matter relies upon pair annihilation of
Weakly Interaction Massive Particles (WIMPs), which is complementary to the
well known techniques of direct detection (WIMP-nucleus scattering) and
collider production (WIMP pair production). Pair annihilation of WIMPs results
in the production of gamma-rays, neutrinos, and anti-matter. Of the various
experiments sensitive to indirect detection of dark matter, the Gamma-ray Large
Area Space Telescope (GLAST) may play the most crucial role in the next few
years. After launch in late 2007, The GLAST Large Area Telescope (LAT) will
survey the gamma-ray sky in the energy range of 20MeV-300GeV. By eliminating
charged particle background above 100 MeV, GLAST may be sensitive to as yet to
be observed Milky Way dark matter subhalos, as well as WIMP pair annihilation
spectral lines from the Milky Way halo. Discovery of gamma-ray signals from
dark matter in the Milky Way would not only demonstrate the particle nature of
dark matter; it would also open a new observational window on galactic dark
matter substructure. Location of new dark matter sources by GLAST would
dramatically alter the experimental landscape; ground based gamma ray
telescopes could follow up on the new GLAST sources with precision measurements
of the WIMP pair annihilation spectrum.
