I think it's interesting that the emphasis on defending something like Rails is based on a comparison to J2EE. My real gripe with Rails is about how it disparages good enterprise-class database practices, and so this is why I'd call it a "toy" system.
That doesn't mean you can't do interesting things with it, but rather that you are essentially talking about an application closely tied to the db schema it stores its data in. The idea of enterprise-class applications sharing their data in a common database is something entirely foreign to (and incompatible with) the Rails way.
This doesn't mean it can't be used in an enterprise environment. For example, you could have a Rails/MySQL app with data imported periodically into a PostgreSQL multi-application database, but I wouldn't call the former "enterprise-class."
That doesn't mean you can't do interesting things with it, but rather that you are essentially talking about an application closely tied to the db schema it stores its data in. The idea of enterprise-class applications sharing their data in a common database is something entirely foreign to (and incompatible with) the Rails way.
This doesn't mean it can't be used in an enterprise environment. For example, you could have a Rails/MySQL app with data imported periodically into a PostgreSQL multi-application database, but I wouldn't call the former "enterprise-class."