Articles about Apache Spark are being published so frequently that we tend not to post most of them on the AMPLab website anymore.   This recent article from the Real-Time Insights blog, however, does a nice job of listing a number of real world use cases, as well as remembering to mention where Spark came from (which not all articles do anymore, ubiquity being a sign of success).   It also describes what is apparently the first commercial integration of SparkR, a more recent AMPLab project.   The article is at: http://www.rtinsights.com/why-apache-spark-is-so-hot/