Spaceflightnow is carrying this story about the discovery of several "stellar highways" circling our Milky Way galaxy. By studying data from the Sloan Digital Sky Survey, scientists have determined there are several narrow "rings" consisting of thousands of stars traveling at several hundred miles per second traveling around the galaxy. It's thought they are the remnants of galactic clusters which were very slowly torn apart by the Milky Way's gravity over billions of years. The streams are being used to explore the properties of dark matter, which appears to affect them different ways in different places.