With the help from pingVision, Popular Science relaunched using Drupal. This move is notable, not only because Popular Science is a popular website, but also because they moved from Vignette v7 (a proprietary content management system) to Drupal (an open source content management system).
According to a recent press release, Vignette's revenue for 2007 was down 3% compared to 2006, and their licensing revenue was down more than 15%. One data point doesn't constitute a trend, but to me, it is further proof that Open Source content management systems are gaining market share. Just last year, Drupal grew by more than 200%.