The problem in trying to output data in the hook_form() method is that the method gets invoked twice which clears the post values the second time through. Throw a dpm($form_state) in the hook_form() function and you'll see two sets of post data. One with values and one without.
So after dissecting the built in Search module, which pretty much operates exactly the way I want my form to work, I figured out how this is done. Well, at least one way you can do it.
What Search module does is take the values from $form_state in hook_form_submit() and pastes them into the URL, then it sets the $form_state['redirect'] to that new URL, effectively storing those variables in the URL and changing the POST to a GET.
Now, in the callback, they extract those values from the URL, do the search on them, THEN they call drupal_get_form(), append the results to the end and return it.
There's another solution HERE where they use SESSION to store the values until the second trip through. Weird, but it works.