FWIW Twitter and Coursera make heavy use of Scala (Twitter also uses Clojure, if you consider Storm etc.)
It is used in production by Twitter, Netflix, Foursquare, LinkedIn, Simple, HealthExpense, Klout, 47 Degrees, Box and a long list of other companies [1].
[1] http://www.quora.com/Startups/What-startups-or-tech-companie...