How do I print the node add form in block.tpl.php?
The drupal_get_form approach is correct. Make sure you use

print drupal_get_form(....


Edit:

Take a look at function node_add(). 
You also need a $node parameter for this form. So like     

&lt;?php
  global user; 
  $node = array('uid' =&gt; $user-&gt;uid, 'name' =&gt; (isset($user-&gt;name) ? $user-&gt;name : ''), 'type' =&gt; 'foo', 'language' =&gt; '');     
  print drupal_get_form('foo_node_form', $node);
?&gt;