It will be generally available in Q1 2019 with support for Ubuntu and RedHat. It will also be the default Java distribution on Amazon Linux.
There is also a docker image, but I don't think it's published to a public registry yet: https://docs.aws.amazon.com/corretto/latest/corretto-8-ug/docker-install.html
Should we consider adding Corretto as a test runtime to our CI configs? Francis