Entity Views Attachment lets you attach a view to a Drupal 7 entity. This means when viewing a node, you could display for example, a list of other nodes by the same author. See http://www.theweek.co.uk/columnist/michael-bywater
But due to the way the views plugin was written, it was not possible to use custom templates for EVA views. If you tried to, you would end up with a lot of 'underfined variable' notices for all the variables in your custom template.
Notice: Undefined variable: title in include() (line 31 of /../sites/all/themes/../templates/eva-display-entity-view--gallery--entity-view-1.tpl.php).
There is a hard dependency on eva.theme.inc even when overriding eva-display-entity-view.tpl.php to a custom tpl. Due to this, template_preprocess_views_view() is not run.
The patch in http://drupal.org/node/1205008#comment-5130160 fixes the above limitation by removing the dependency from hook_views_plugins().