Is GNU R (an environment for statistical computing) suitable enough for Biostatisticians involved in Clinical Research? Can it replace or support SAS in this area? Well, I think this presentation may help to remove any doubts. If you are a Biostatistician (and probably a SAS user), you may find it useful.
The presentation is under constant improvement.
You can find it also on CRAN (contributed documentation) and at http://www.r-clinical-research.com