Spark is hot

It's also very hot. If you go to this web page here, it will give you a list of some known people that are using Spark: https://cwiki.apache.org/confluence/display/SPARK/Powered+By+Spark

A lot of big companies are kind of secretive about what they're doing inside, so I'm sure there are even more people using it than what are listed here, but we know a lot of the big players are already using Spark: Amazon, eBay, NASA's Jet Propulsion Laboratory, Yahoo, and many others. The list isn't as long as MapReduce because Spark hasn't been around as long as MapReduce, but it's definitely getting some big adoption quickly.