How to get $form_state['values'] after a drupal_get_form() call?
I realise this is an old question but: drupal_get_form() is mostly a wrapper for drupal_build_form(), and (the docs say) is intended to be used "instead of drupal_build_form() when $form_state is not needed", with the implication that if $form_state is needed, it's OK to go straight to drupal_build_form().

The only extra bit drupal_get_form does is assemble a 'build_info' array in the $form_state, so instead of (e.g.) $block['content']['form'] = drupal_get_form('myform_name', $arg);, you could do something like this:

  $form_state = array();
  $form_state['build_info']['args'][] = $arg;
  $block['content']['form'] = drupal_build_form('myform_name', $form_state);


You should find your $form_state variable is now populated as it would be if you were operating inside the form building function, including any $form_state['values'] or $form_state['input'] in the event that your form is being rebuilt.