The timeout exception is trapped by the Failure clause of Try.

gistfile1.scala

[info] Starting scala interpreter...
[info] 
Welcome to Scala version 2.10.0 (Java HotSpot(TM) 64-Bit Server VM, Java 1.6.0_43).
Type in expressions to have them evaluated.
Type :help for more information.

scala> import scala.util.Try
import scala.util.Try

scala> import scala.util.{Success, Failure}
import scala.util.{Success, Failure}

scala> import scala.concurrent._
import scala.concurrent._

scala> import scala.concurrent.duration._
import scala.concurrent.duration._

scala> import ExecutionContext.Implicits.global
import ExecutionContext.Implicits.global

scala> val f = future[Int]{ do{} while(true); 1 }
f: scala.concurrent.Future[Int] = scala.concurrent.impl.Promise$DefaultPromise@9695ed7

scala> def foo = Try { Await.result(f, 3 seconds) }
foo: scala.util.Try[Int]

scala> foo match {
     |   case Success(i) => println(i)
     |   case Failure(f) => println(f.getMessage)
     | }
Futures timed out after [3 seconds]

scala>