Scala 2.11.0-RC1 is now available(scala-lang.org)

     scala> Option(3) match { case Some(nr) => println(nr) }
     <console>:9: warning: match may not be exhaustive.
     It would fail on the following input: None

     val stillAMap: Map[String, String] = Map("hello" -> "world").map { 
       case (key, value) => (key, value + ", Alex") 
     }

     val iterOfInt: Iterable[Int] = Map("hello" -> "world").map { 
       case (key, value) => value.length
     }

     val iterOfAny: Iterable[Any] = iterOfInt

     trait Foo {
       def isOperational: Boolean
       def isDispatched: Boolean
     }

     object Available extends Foo {
       val isOperational = true
       val isDispatched = false
     }

     object RampUp extends Foo {
       val isOperational = true
       val isDispatched = true
     }

     object Fault extends Foo {
       val isOperational = false
       val isDispatched = false       
     }

     // ...

     trait Foo

     trait IsOperational extends Foo
     trait IsNotOperational extends Foo
     trait IsDispatched extends Foo
     trait IsNotDispatched extends Foo

     object Available extends IsOperational with IsNotDispatched
     object RampUp extends IsOperational with IsDispatched
     object Fault extends IsNotOperational with IsNotDispatched
     // ...

     object IsDispatched {
       def unapply(state: IsOperational) = state match {
         case ref: IsDispatched => Some(ref)
         case _ => None
       }
     }