Detecting Dark Matter

Telescopes may soon be able to "see" the Universes dark matter - all that stuff in space that does not emit any light. Astronomers have succeeded in locating and weighing a galaxy cluster solely by the effect its gravity has on light from more distant objects. Within a decade, their work could lead to a 3D map of the Universes dark matter, which outweighs visible stars and galaxies by at least a factor of 10. The astronomers exploited the phenomenon of "gravitational lensing", in which light from very distant galaxies is distorted by the gravity of massive objects situated in a direct line between them and Earth. The shape and extent of the distortion tell you about the location and mass of the intervening matter.
http://www.newscientist.com/news/news.jsp?id=ns99991187