http://devnet.jetbrains.net/thread/436214?tstart=0

compiler/cli/src/org/jetbrains/jet/cli/common/CompilerVersion.java

@@ -22,5 +22,5 @@ package org.jetbrains.jet.cli.common;
 public class CompilerVersion {
     // The value of this constant is generated by the build script
     // DON'T MODIFY IT
-    public static final String VERSION = "@snapshot@";
+    public static final String VERSION = "snapshot";
 }

compiler/cli/src/org/jetbrains/jet/cli/js/K2JSCompiler.java

@@ -121,8 +121,8 @@ public class K2JSCompiler extends CLICompiler<K2JSCompilerArguments, K2JSCompile
     @NotNull
     private static Config getConfig(@NotNull K2JSCompilerArguments arguments, @NotNull Project project) {
         if (arguments.libzip == null) {
-            return Config.getEmptyConfig(project);
+            return Config.getEmptyConfig(project, arguments.target);
         }
-        return new ZippedLibrarySourcesConfig(project, arguments.libzip);
+        return new ZippedLibrarySourcesConfig(project, arguments.libzip, arguments.target);
     }
 }

compiler/cli/src/org/jetbrains/jet/cli/js/K2JSCompilerArguments.java

@@ -38,6 +38,9 @@ public class K2JSCompilerArguments extends CompilerArguments {
     @Argument(value = "srcdir", description = "Sources directory")
     public String srcdir;
 
+    @Argument(value = "target", description = "Generate js files for specific ECMA version (3 or 5, default ECMA 3)")
+    public String target;
+
     @Argument(value = "tags", description = "Demarcate each compilation message (error, warning, etc) with an open and close tag")
     public boolean tags;