PLoS ONE today published a paper very relevant to Open Access Week (which started today): Gargouri Y, Hajjem C, Larivière V, Gingras Y, Carr L, Brody T, Harnad S. Self-Selected or Mandated, Open Access Increases Citation Impact for Higher Quality Research. PLoS ONE. 2010;5(10):e13636+. doi:10.1371/journal.pone.0013636.