The Scientist has come up with a list of the top five hottest papers of 2009. Drawing on information from ScienceWatch and ISI, it reports that the top two topics of the year were stem cells and, no surprise to us here, genomics. The second-to-top paper is the Frazer et al Nature paper on the latest HapMap. And coming in first is the Yamanaka group's work on inducing pluripotent stem cells.