Well, just as if we didn’t have enough to keep track of in particle physics, along comes another claim that dark matter has been detected, by looking for extremely rare and faint signals of collisions of dark matter particles with atomic nuclei in a special type of crystal.
The abstract from the paper http://arxiv.org/PS_cache/arxiv/pdf/1109/1109.0702v1.pdf says (paraphrasing when necessary to make it somewhat lay-person-interpretable)
The CRESST-II Dark Matter search, aiming at detection of “WIMPs” (hypothetical dark-matter particles that feel the weak nuclear force) through their scattering off atomic nuclei in CaWO4 crystals, [presents] data collected with eight detector modules, which can detect the energy deposited when a dark matter particle strikes a nucleus, and distinguish (on average) a real dark matter particle collision from various backgrounds that could fake a signal. Sixty-seven events are found. We estimate background contributions to this observation from four sources, but find, at a high statistical significance, that these sources alone are not sufficient to explain the data. The addition of a signal due to scattering of relatively light WIMPs could account for this discrepancy, and we determine the mass and interaction strength of such a WIMP that would be required.
How excited should we get? The subject is murky. This is not the first dark matter experiment to claim a detection of this type, yet no two experiments that have made such claims have ever seen evidence of the same thing. And a first glance at this paper shows it is very complicated, and not particularly clear. Moreover, this experimental collaboration has been somewhat obscure about its previous results. And finally, the effect they see would appear, naively, already to have been excluded by some other experiments (you can even see this in figure 13 of this very paper.)
These are very tough measurements; estimating the various backgrounds, which they claim are too small to explain what they observe, is very difficult. It would be hard to be confident of their results until another experiment, or an upgrade of this one, sees the same result. With any hint of a discovery, healthy skepticism is warranted, but perhaps a bit more than usual is needed here initially, at least until the super-experts have looked this one over.