Place output of a custom module in a specific region
If some variable you are looking for isn't available in the scope of your hook, there is a good chance that you are doing it wrong. 

Title of the page can be accessed in your theme's page.tpl.php file (or its variants). You can use a hook_preprocess_page() in your template.php file and populate a new variable if the path matches (node add forms have node/add path) so you can put it in the appropriate sidebar in the page.tpl.php. 

You cannot control stuff to be shown in the page with a form_alter hook. 
For Drupal 7, you could use hook_page_alter() or hook_page_build() to inspect and set sidebar contents. 

For an example:

template.php:

function mytheme_preprocess_page (&amp;$variables) {
  if (arg(0) == 'node' &amp;&amp; arg(1) == 'add' &amp;&amp; arg(2) &amp;&amp; isset($vars['page']['content']['system_main']['nid'])) {
    $variables['sidebar_title'] = t('Create new @type', array('@type' =&gt; arg(2)))
  }
}


Now, print the sidebar title in your page.tpl.php's appropriate div. 

if (isset($sidebar_title)) {
  print $sidebar_title;
}


Drupa.org article: Setting up variables for use in a template (preprocess and process functions)