The standard model of cold dark matter (CDM) predicts the existence of thousands of small dark matter halos orbiting the Milky Way, and steep cusps in the central regions of dark matter halos. The dark matter dominated satellite galaxies of the Milky Way provide an ideal laboratory to test these predictions, and thus place strong constraints on the nature of dark matter. I will show how current observations, including those from newly discovered satellites, test solutions to the CDM "missing satellites problem," and how future astrometric data will reveal the presence of dark matter cores or cusps. I will also discuss updated and new prospects for indirect dark matter detection.