Today I have released easy authcache 2 - module that provide api for easy implementation server side includes with different tools.
For now easy authcache 2 support Varnish ESI and drupal Authcache ways to include dynamic html.
In future going to add support SSI. Support server side includes will be usefull for using drupal+nginx.
Modules that provide way making server side include called - plugins. There are additional modules that implements easy authcache 2 api for different drupal modules. Drupal block implementation was ported from easy authcache 1. In a few weeks will be ported implementation of comments, plus1 and views modules.
Also functionality for generation varnish config is in plans.
Patches are wellcome.