This is a very nice feature from Amazon that allows the adoption of a more scalable and secure infrastructure.
Dear Amazon Web Services Customer,
We are excited to announce that you can now create a load balancer in your Amazon Virtual Private Cloud (“VPC”) for internal load balancing. With this new feature, you can balance requests between tiers of your application using the private IP addresses of the load balancer, enabling you to use a load balancer without being required to expose it to the internet. For example, if you have a web server front-end that makes requests to application server instances, you can now place a load balancer in front of the application server instances and send the requests from the web server to the internal load balancer. You can still use the Elastic Load Balancing features such as session stickiness, SSL encryption, health checks, and instance registration and de-registration.
To learn more, visit the Elastic Load Balancing page or view the Elastic Load Balancing Developer Guide.