Organic Groups (7.23) and D7 | drush or cmdline integration?
I started, but never had time to finish Drush commands for og-6.x-1.x.  Please see https://drupal.org/node/1090438 for the preliminary implementation.  I don't know why no one else has picked this up; I agree it would be useful.

For og-7.x-2.x, I do some programmatic operations in my sandbox project https://drupal.org/sandbox/greg1anderson/2049677.  These are not broken out into direct og operations, but it might serve as a starting point for someone who wanted to pick up the task of adding Drush commands to organic groups.

Finally, for anyone who wants to quickly make a Drush command from a template, see https://drupal.org/project/drushify.