Amazon has dropped more crumbs in the forest to entice the enterprise to ultimately abandon its own infrastructure for its doubtlessly cheaper public cloud.

It's making its Virtual Private Cloud (VPC), which used to be separate service, a free default.

It said in a blog that the announcement was so important "If you use or plan to use Amazon EC2, you need to read this post!"

Undoubtedly VMware and other cloud merchants won't care much for this turn of events.

Amazon is starting what it called its EC2-VPC roll-out in its regions in Sydney (Asia-Pacific) and São Paulo (South America). It'll branch out elsewhere in the next few weeks.

The free offer is only open to new customers and accounts that haven't used those regions before. Existing AWS customers can try the new stuff if they create a new AWS account or pick a region they haven't used before.

Amazon's Virtual Private Cloud (VPC) will be configured automatically when the user launches an EC2 instance or provisions Elastic Load Balancers, RDS databases or ElastiCache clusters like one normally would.

Amazon will launch the necessary resources and assign each EC2 instance a public IP address. Users can then assign multiple IP addresses to an instance, change security group membership on-the-fly and add egress filters to their security groups if they want.

Nobody's code has to be modified. The widgetry is designed to be compatible with the user's existing shell scripts, CloudFormation templates, Elastic Beanstalk apps and auto-scaling configurations.

Amazon makes a distinction between EC2-VPC and what it's now calling EC2-Classic, its more complicated, four-year-old way of setting up VPCs by creating a virtual network of logically isolated EC2 instances and an optional VPN connection to one's own data center.

Amazon has also added features to VPC like DNS hostnames, DNS name resolution, ElastiCache and RDS IP addresses.

It is also offering a third way to create a non-default VPC that isn't set up automatically.

See http://aws.typepad.com/aws/2013/03/amazon-ec2-update-virtual-private-clouds-for-everyone.html and http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-vpc.html#differences.