gearing up for 0.0.41 with an updated post_install message

Rakefile

@@ -20,6 +20,18 @@ begin
     gem.rubyforge_project = "fog"
 
     gem.post_install_message = <<MESSAGE
+#{'=' * 50}
+
+  fog 0.0.41 has a minor change to the API for ec2 servers:
+
+    # what_it_was => what_it_is
+
+    ec2.servers.new(:group_id => 'foo') => ec2.servers.new(:groups => ['foo'])
+
+  Updating to the newest api version also means you can now assign multiple groups:
+
+    ec2.servers.new(:groups => ['foo', 'bar'])
+
 #{'=' * 50}
 
   fog 0.0.40 has API changes you should know about.