The pubsub code has a load of helper functions to build stanzas for various pubsub actions, where the caller can optionally pass addresses to store pointers to the <pubsub> node, the <create> node, etc. Currently they all look like this:

WockyXmppStanza *
wocky_pubsub_blah_create_foo_stanza (
   WockyPubsubBlah *self,
   WockyPubsubNode **pubsub_node,
   WockyPubsubNOde **foo_node)
{
  WockyPubsubStanza *stanza;
  WockyPubsubNode *pubsub, *foo;

  stanza = build (...,
      SHOUTY SHOUTY,
        SHOUTY_ASSIGN_TO, &pubsub, ..... );

  if (pubsub_node != NULL)
    *pubsub_node = pubsub;
}

It might be nice to let build accept NULL targets, and just not assign in that case. On the flipside, it arguably makes it harder to detect you screwing up.