Is drupal_get_form('webform_client_form_XXX') supposed to work?

You have to pass in all the form parameters. I've included them all here as variables for a clear example.

  $submission = array();
  $enabled = TRUE;
  $preview = FALSE;
  print drupal_get_form('webform_client_form_XXX', $node, $submission, $enabled, $preview);

You should read the PHP Doc for webform_client_form() where each of the parameters is documented (or should be :P). We probably could set defaults for most of the parameters, but I haven't seen many people calling drupal_get_form() to get a webform directly.

The $node object is the node containing the webform. If you don't have it already you can load the webform like this:

  $node = node_load($nid);

In drupal 7

  $submission = array();
  $enabled = TRUE;
  $preview = FALSE;
  print drupal_get_form('webform_client_form_XXX', $node, $submission, $enabled, $preview);

did not work

  $submission = (object) array();
  $enabled = TRUE;
  $preview = FALSE;
  print drupal_get_form('webform_client_form_XXX', $node, $submission, $enabled, $preview);

this does...

Is there any advantage to this rather than making the Webform available as a block, and then embedding the block in your node template?

@goldhat
in my case i needed the webform in a ctools modal frame.
was "easier" this way.

In drupal 6 this is what worked for me:

Where XXX is the node id.

<?php 
$webform = webform_block_view($delta = 'client-block-XXX');
print $webform['content']; 
?>

... And works Ok on Drupal 7

I have a solution that outputs the same html as working example in your post @rv()

I was working on a similar problem but I had to return the form in a JSON object to be displayed in a web app.

$node = node_load($node_id);
webform_node_view($node,'full');
$node_rendered = theme_webform_view($node->content);

then you can print the $node_rendered or return it inside of a JSON object

Old posts, but this comes up high in Google. So if anyone else is looking to embed a webform in views on Drupal 7, number 9 actually works in getting the form to pull up in a views footer. I tried all the other posts in here and post #9 in here was the only one that worked.

$node = node_build_content(node_load(10));
$submission = array();
$enabled = TRUE;
$preview = FALSE;
        
drupal_get_form('webform_client_form_10', $node, $submission, $enabled, $preview);

You don't need the submission or enabled parts, In fact those are no longer the proper arguments for the function. (In this case they won't really hurt anything, but it will add confusion.)

<?php
$node = node_build_content(node_load(10));
$node_webform = drupal_get_form('webform_client_form_10', $node);
drupal_render($node_webform);
?>

#14 It doesn't work :( .