You can also go back to the FAQ page.
Attempting to build Scala on PowerPC OS X results in various errors. These can range from an internal compiler error to a Trace/BPT trap. It is claimed that Java 1.5.0_06 in JITed mode (HotSpot) on PPC OS X has bugs in object reference handling.
Scala builds successfully on OS X with JDK 1.6.
Check out David Bernard’s blog, maven for scala.