Code from a tutorial on creating a Galleriffic + WordPress Gallery post format (http://zoerooney.com/blog/tutorials/using-galleriffic-galleries-for-the-gallery-post-format/)

galleriffic-post-format.php

<?php if ( has_post_format( 'gallery' )) { ?>
  <div class="controls"></div>
  <div class="slideshow"></div>
  <div class="captionbox"></div>
  <div class="thumb-wrapper">
    <?php $images = get_children( array( 'post_parent' => $post->ID, 'post_type' => 'attachment', 'post_mime_type' => 'image', 'post_status' => null, 'orderby' => 'menu_order', 'order' => 'ASC', 'numberposts' => -1 ) );
    if( $images ): ?>
      <ul class="thumbs noscript">
        <?php foreach( $images as $attachment_id => $attachment ): ?>
          <li>
              <a class="thumb" href="<?php echo wp_get_attachment_url( $attachment_id ); ?>" title="<?php echo $attachment->post_title; ?>">
                  <?php echo wp_get_attachment_image( $attachment_id, 'thumbnail' ); ?>
              </a>
              <div class="caption">
                  <?php echo $attachment->post_excerpt; ?>
              </div>
          </li>
          <?php endforeach; ?>
      </ul>
      <?php endif; ?>
  </div>
  <script>
  jQuery(document).ready(function($){
    $('.thumb-wrapper').each(function(){
        $(this).galleriffic({
            imageContainerSel: $(this).parent().children('.slideshow'),
            controlsContainerSel: $(this).parent().children('.controls'),
            captionContainerSel: $(this).parent().children('.captionbox')
        });
    });
  });
  </script>
<? } ?>

jquery-init.js

jQuery(document).ready(function($){
  $('.thumb-wrapper').each(function(){
    $(this).galleriffic({
      imageContainerSel: $(this).parent().children('.slideshow'),
      controlsContainerSel: $(this).parent().children('.controls'),
      captionContainerSel: $(this).parent().children('.captionbox')
    });
  });
});

markup.html

<div class="controls"></div>
<div class="slideshow"></div>
<div class="captionbox"></div>

<div class="thumb-wrapper">
    <!-- This is where we grab all the attached images -->
    <ul class="thumbs noscript">
      <!-- This is where we loop through the images -->
        <li>
          <!-- Everything in here is the same as before, see the full code below -->
        </li>
      <!-- The foreach ends here -->
    </ul>
    <!-- Our conditional from grabbing the images ends here -->
</div>

post-format-conditional.php

if ( has_post_format( 'gallery' )) {
  // everything in here is only shown for this post format
}

post-format.php

add_theme_support( 'post-formats', array( 'gallery' ) );