add post install message

Rakefile

@@ -21,6 +21,17 @@ begin
     gem.add_development_dependency('mocha')
     gem.add_development_dependency('flexmock')
     gem.add_development_dependency('rr')
+    gem.post_install_message = <<-EOM
+#{"*"*50}
+
+  Thank you for installing #{gem.summary}
+
+  The 'a' in #{gem.version} means this is alpha software.
+  If you are looking for a supported production release,
+  please "gem install rspec" (without --pre).
+  
+#{"*"*50}
+EOM
   end
 rescue LoadError
   puts "Jeweler (or a dependency) not available. Install it with: gem install jeweler"

rspec-mocks.gemspec

@@ -83,6 +83,16 @@ Gem::Specification.new do |s|
      "spec/support/macros.rb"
   ]
   s.homepage = %q{http://github.com/rspec/mocks}
+  s.post_install_message = %q{**************************************************
+
+  Thank you for installing rspec-mocks-2.0.0.a7
+
+  The 'a' in 2.0.0.a7 means this is alpha software.
+  If you are looking for a supported production release,
+  please "gem install rspec" (without --pre).
+  
+**************************************************
+}
   s.rdoc_options = ["--charset=UTF-8"]
   s.require_paths = ["lib"]
   s.rubyforge_project = %q{rspec}