Seth Hoedl and Svenja Fleischer, along with the Eöt-Wash faculty, have conducted an experiment to search for forces mediated by the theoretically-proposed and as-yet-undetectable axion. The axion is one of the leading dark matter candidates.
The first results from this experiment may be found here: http://prl.aps.org/abstract/PRL/v106/i4/e041801 (local PDF is coming!).
Work continues on an improved version of the experiment.