diff --git a/Rakefile b/Rakefile
index e42cd8c..a85b478 100644
--- a/Rakefile
+++ b/Rakefile
@@ -57,6 +57,28 @@ module Koans
   end
 end
 
+module RubyImpls
+  # Calculate the list of relevant Ruby implementations.
+  def self.find_ruby_impls
+    rubys = `rvm list`.gsub(/=>/,'').split(/\n/).sort
+    expected.map { |impl|
+      puts "DBG: impl=#{impl.inspect}"
+      last = rubys.grep(Regexp.new(Regexp.quote(impl))).last
+      last ? last.split.first : nil
+    }.compact
+  end
+
+  # Return a (cached) list of relevant Ruby implementations.
+  def self.list
+    @list ||= find_ruby_impls
+  end
+
+  # List of expected ruby implementations.
+  def self.expected
+    %w(ruby-1.8.6 ruby-1.8.7 ruby-1.9.2 jruby ree)
+  end
+end
+
 task :default => :walk_the_path
 
 task :walk_the_path do
@@ -107,3 +129,38 @@ SRC_FILES.each do |koan_src|
     Koans.make_koan_file koan_src, t.name
   end
 end
+
+task :run do
+  puts 'koans'
+  Dir.chdir("src") do
+    puts "in #{Dir.pwd}"
+    sh "ruby path_to_enlightenment.rb"
+  end
+end
+
+
+desc "Pre-checkin tests (=> run_all)"
+task :cruise => :run_all
+
+desc "Run the completed koans againts a list of relevant Ruby Implementations"
+task :run_all do
+  results = {}
+  RubyImpls.list.each do |impl|
+    puts "=" * 40
+    puts "On Ruby #{impl}"
+    res = sh "rvm #{impl} rake run"
+    results[impl] = res
+    puts
+  end
+  puts "=" * 40
+  puts "Summary:"
+  puts
+  results.each do |impl, res|
+    puts "#{impl} => RAN"
+  end
+  puts
+  RubyImpls.expected.each do |requested_impl|
+    impl_pattern = Regexp.new(Regexp.quote(requested_impl))
+    puts "No Results for #{requested_impl}" if results.keys.grep(impl_pattern).empty?
+  end
+end
diff --git a/koans/about_java_interop.rb b/koans/about_java_interop.rb
index 20a40c7..66f79c4 100644
--- a/koans/about_java_interop.rb
+++ b/koans/about_java_interop.rb
@@ -95,6 +95,19 @@ class AboutJavaInterop < EdgeCase::Koan
     assert_equal __, java_array.toString.is_a?(java.lang.String)
   end
 
+  def test_some_ruby_objects_can_be_coerced_to_java
+    assert_equal __, "ruby string".to_java.class
+    assert_equal __, 1.to_java.class
+    assert_equal __, 9.32.to_java.class
+    assert_equal __, false.to_java.class
+  end
+
+  def test_some_ruby_objects_can_NOT_be_coerced_to_java
+    assert_equal __, [].to_java.class == Java::JavaUtil::ArrayList
+    assert_equal __, {}.to_java.class == Java::JavaUtil::HashMap
+    assert_equal __, Object.new.to_java.class == Java::JavaLang::Object
+  end
+
   def test_java_collections_are_enumerable
     java_array = java.util.ArrayList.new
     java_array << "one" << "two" << "three"
diff --git a/src/about_java_interop.rb b/src/about_java_interop.rb
index 39a93b7..56035db 100644
--- a/src/about_java_interop.rb
+++ b/src/about_java_interop.rb
@@ -95,6 +95,19 @@ class AboutJavaInterop < EdgeCase::Koan
     assert_equal __(false), java_array.toString.is_a?(java.lang.String)
   end
 
+  def test_some_ruby_objects_can_be_coerced_to_java
+    assert_equal __(Java::JavaLang::String), "ruby string".to_java.class
+    assert_equal __(Java::JavaLang::Long), 1.to_java.class
+    assert_equal __(Java::JavaLang::Double), 9.32.to_java.class
+    assert_equal __(Java::JavaLang::Boolean), false.to_java.class
+  end
+
+  def test_some_ruby_objects_can_NOT_be_coerced_to_java
+    assert_equal __(false), [].to_java.class == Java::JavaUtil::ArrayList
+    assert_equal __(false), {}.to_java.class == Java::JavaUtil::HashMap
+    assert_equal __(false), Object.new.to_java.class == Java::JavaLang::Object
+  end
+
   def test_java_collections_are_enumerable
     java_array = java.util.ArrayList.new
     java_array << "one" << "two" << "three"