Scala has been a breath of fresh air for Java developers looking to take advantage of more powerful constructs -- such as Scala Actors for concurrency -- all without loosing the capability to execute applications on Java's Virtual Machine. But as this post by Wille Faler points out, there are still a few gotchas to combining Scala with techniques you may have relied using the Java language, one such case being the Java Persistence API(JPA). Read Wille Faler's post 'Scala + JPA, some gotcha’s to be aware of': http://faler.wordpress.com/2009/08/10/scala-jpa-some-gotchas-to-be-aware-of/