Yes but there are a lot of ways that "the containers are linked together" could be implemented and some of them e.g. key value store require modifying application code quite a bit whereas e.g. DNS does not.
Wasn't there just an AWS announcement yesterday about the ability to register VPC-private DNS records in Route 53? It screamed "SkyDNS competitor" to me but I couldn't figure out what Amazon wanted such a thing for. Makes sense now.
Route 53 launched private (vpc) dns last week. Its actually a common pattern to manage ec2 instances via dns records. Many people had built this on top of the public route53 offering, see zonify from airbnb as an example. Private dns improves on that model as the vpc instances never have to communicate with the public internet now.