Dark Matter Mysteries Deepen

Wired has a nice article on recent research reporting surprising observations that may relate to dark matter. A brief excerpt:
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. dark matter is thought to barely interact with itself. The dark matter should just coast through itself and move at the same speed as the hardly interacting galaxies. Instead, it looks [with the recent observations] like the dark matter is crashing into something — perhaps itself – and slowing down faster than the galaxies are. But this would require the dark matter to be able to interact with itself in a completely new an unexpected way, a “dark force” that affects only dark matter. This would be a new fundamental force of the universe, in addition to the four known forces: gravity, electromagnetism, and the strong and weak forces.
...[If this new property is correctly supposed] in particular it would help solve the core/cusp problem, an outstanding mystery seen in dwarf galaxies and star clusters. If dark matter only feels the force of gravity, it should tend to clump in the center of these objects. But astronomers over and over observe the opposite: The dark matter in dwarf galaxies and star clusters is evenly distributed. If dark matter can interact through some sort of dark force, it can bump into itself and puff out, like a hot gas.