Our ServiceMix 5 project is the first piece of Apache ServiceMix that is being developed using Scala instead of Java.
On this page, you'll find a few links to useful resources about (getting started with) Scala, recommended by members of the Apache ServiceMix community to ease your transition into the Scala world.
Odersky, M., Spoon, L., and Venners, B. (2011) Programming Scala 2nd Ed. Artima Inc. (publisher book info)
Subramaniam, V. (2009) Programming Scala. Pragmatic Bookshelf. (publisher book info)