bash-3.00$ scalac -Xrtt test.scala
bash-3.00$ scala -cp . Test
Exception in thread "main" java.lang.NoSuchMethodError: scala.List.$colon$colon(Lscala/Type;Ljava/lang/Object;)L\
scala/List;
        at Test$.(test.scala:2)
        at Test$.(test.scala)
        at Test.main(test.scala:45)

This is because your copy of the library wasn't compiled with run time types enabled. Making run time types work is slightly harder than what Burak said: you have to recompile the whole library and compiler with the option enabled for things to work, and hack the RefCheck phase first to disable a small check. You should ask Stéphane, who nows how to do this.

Apart from that you (the LAMP that is) should find a new maintainer for run time types, as I won't work on the compiler any longer, so assigning bugs to me now is a good way to have them ignored :-) [the current bug being the exception which will confirm the rule].