In Lang and my April Fool's post, arXiv/1103.6038, we made use of an affine-invariant MCMC sampler proposed by Goodman and Weare, which has very good autocorrelation properties. That is, it greatly reduces the number of likelihood calls you need to make to reach good results. Today, I worked a bit on (and then signed off on) Fengji Hou's paper on a general implementation of this sampler and application of it in exoplanet discovery.
(By the way, we tried to come out first on April 1, submitting 48 seconds after the deadline. There were seven papers in—or cross-listed in—astro-ph in the first 8 seconds after the deadline. You gotta be fast.)