From Gizmodo. com comes this nice summary of the latest publications about those mystery spots on Ceres. Read it here:

http://gizmodo.com/we-finally-have-the-full-story-on-ceres-mysterious-brig-1746997700

Using their new camera settings, Nathues and his colleagues acquired high-resolution images of the entire surface of Ceres, allowing them to pick out numerous bright spots against an asphalt-colored background. All in all, Ceres bears over 130 glimmering splotches, ranging in brightness from that of concrete to ocean ice. Often, these features are associated with impact craters. Based on precise measurements of their brightness, we can now conclude that the main material in the spots is indeed a salt—more specifically, hydrated magnesium sulfate.