This build uses a new method to replace the form state /before/ a form gets built. This requires a core patch to add a drupal_alter to drupal_get_form. Adding a core patch is not ideal, but avoids any weirdness of building the same form twice.
This is the first release of the drafts module. This is very much in alpha at the moment. Things will be fluctuating a lot while practical and security concerns are ironed out.
Features:
Saves entity forms by way of adding a field.
Provides a "Drafts" tab to the content administration page.
Uses a custom JS library to scrape form data (integrating with FAPI #ajax).