This issue could perhaps start with adding some warning about untested scala versions, including a link to some kind of living documentation (doc.etherpad.org somewhere?) on which scala versions are workable.

Another Scala version problem; a short thread
http://groups.google.com/group/etherpad-open-source-discuss/t/a74309c69885b1a3
which ended "Fixed it by downgrading to 2.7.4 Should have checked the forum first."

/usr/local/etherpad/infrastructure/net.appjet.bodylock/bodylock.scala:46: error: inferred type arguments [scala.collection.Map[String,String]{def empty: scala.collection.Map[String,String]{def empty: scala.collection.Map[String,String]{def companion: scala.collection.generic.GenericCompanion[Iterable[Any]]}; def companion: scala.collection.generic.GenericCompanion[Iterable[Any]]}; def companion: scala.collection.generic.GenericCompanion[Iterable[Any]{def companion: scala.collection.generic.GenericCompanion[Iterable[Any]]}]}] do not conform to method getOrElse's type parameter bounds [B >: scala.collection.mutable.SynchronizedMap[String,String]]
val code = BodyLock.map.getOrElse(MapString, String).getOrElse(elt.getFileName, "").split("\n"); // 0-indexed.
^
/usr/local/etherpad/infrastructure/net.appjet.bodylock/bodylock.scala:64: error: inferred type arguments [scala.collection.Map[String,String]{def empty: scala.collection.Map[String,String]{def empty: scala.collection.Map[String,String]{def companion: scala.collection.generic.GenericCompanion[Iterable[Any]]}; def companion: scala.collection.generic.GenericCompanion[Iterable[Any]]}; def companion: scala.collection.generic.GenericCompanion[Iterable[Any]{def companion: scala.collection.generic.GenericCompanion[Iterable[Any]]}]}] do not conform to method getOrElse's type parameter bounds [B >: scala.collection.mutable.SynchronizedMap[String,String]]
val code = BodyLock.map.getOrElse(MapString, String).getOrElse(cause.sourceName(), "").split("\n"); // 0-indexed.
^
/usr/local/etherpad/infrastructure/net.appjet.bodylock/bodylock.scala:150: error: not found: type byte
def executableFromBytes(bytes: Array[byte], className: String) =
^
three errors found
/usr/local/etherpad/infrastructure/ace/bin/make:22: error: missing arguments for method collect in trait Iterator;
follow this method with _' if you want to treat it as a partially applied function "@|[a-zA-Z0-9]+|[^@a-zA-Z0-9]{1,3}").r.findAllIn(input).collect.toArray; ^ /usr/local/etherpad/infrastructure/ace/bin/make:46: error: missing arguments for method collect in trait Iterator; follow this method with' if you want to treat it as a partially applied function
}).collect:*);
^
/usr/local/etherpad/infrastructure/ace/bin/make:49: error: value mkString is not a member of Array[Nothing]
val afterReplace = toks.map(encode(_)).mkString.replaceAll(
^
three errors found
cp: cannot stat `/usr/local/etherpad/infrastructure/build/appjet.jar': No such file or directory

See http://github.com/ether/pad/pull/179