Bob Muenchen has recently updated his report on the popularity of statistical software. With the updated analysis, we see that the R community remains as strong as ever: the number of contributed R packages continues its exponential growth rate, R maintains its dominance in online discussion, and has 20x the content of other statistics packages on social programming sites like CrossValidated and StackOverflow.
One particularly interesting metric is the number of times software packages are cited in scholarly articles, as a measure of the rate at which such packages are used in academia. Google Scholar makes it possible to quantify such measures, and from the chart below we can see that SAS and SPSS have been on a steep decline since around 2005 or so:
Amongst the software packages showing growth in academia (i.e. all those except SAS and SPSS), R is has the largest "market share" of citations, and continues to grow rapidly:
If you're interested in the details of how market share was calculated, or how to create a "market share" plot like this using the ggplot2 package, the librestats blog has everything you need at the link below.