R is now used by 52.5% of poll respondents, compared with 45% last year. Donnie Berkholz provides an analysis of the year-on-year trends for Redmonk. He provides the chart below, and notes "the general trend of newer, open-source languages growing at varying speeds (Python followed by R and Hadoop-based options like Hive/Pig), while older languages including Java, SAS, and Matlab are bleeding users".
Meanwhile, the recently-released Rexer Analytics 2011 Data Miner Survey also ranks R #1 amongst data miners overall, and also for corporate, consulting, academic and government use:
The complete report of the Rexer Data Mining Survey is available on request from Rexer Analytics.
If you're interested in using R for data mining, check out the Revolution Analytics webinar, Introduction to to R for Data Mining.