$ scalac test.scala
test.scala:16: error: type mismatch;
 found   : T
 required: java.lang.Object
Note that implicit conversions are not applicable because they are ambiguous:
 both method any2stringadd in object Predef of type (Any)scala.runtime.StringAdd

 and method any2ArrowAssoc in object Predef of type [A](A)ArrowAssoc[A]
 are possible conversion functions from T to java.lang.Object
     override def initialValue = init;
                                 ^
one error found

ricky@ricky-PB ~/deleteme
$ scalac -Ygenerics test.scala
test.scala:16: error: type mismatch;
 found   : T
 required: Nothing
     override def initialValue = init;
                                 ^
test.scala:20: error: type mismatch;
 found   : T
 required: Nothing
   def := (t : T) = value.set(t);
                              ^
two errors found

ricky@ricky-PB ~/deleteme
$ scalac -version
Scala compiler version 2.6.0-final -- (c) 2002-2007 LAMP/EPFL