I was wondering if it’s possible to display a field based on the fact of whether or not a file field has any images selected or not. Unfortunately it didn’t work, but I tried this:

piklist('field', array(
  'type'    => 'group',
  'field'   => 'features',
  'label'   => 'Features',
  'add_more'=> true,
  'fields'  => array(
    array(
      'type'    => 'text',
      'field'   => 'title',
      'label'   => 'Title',
      'columns' => 12
    ),
    array(
      'type'    => 'textarea',
      'field'   => 'description',
      'label'   => 'Description',
      'columns' => 12,
      'attributes'  => array(
        'rows'        => 4
      )
    ),
    array(
      'type'    => 'file',
      'field'   => 'image',
      'label'   => 'Featured Image',
      'columns' => 12
    ),
    array(
      'type'    => 'radio',
      'field'   => 'image-alignment',
      'label'   => 'Image Alignment',
      'columns' => 12,
      'value'   => 'bottom',
      'list'    => false,
      'choices' => array(
        'align-top'     => 'Top',
        ''              => 'Center',
        'align-bottom'  => 'Bottom'
      ),
      'conditions'  => array(
        array(
          'field'   => 'features:image',
          'compare' => '!=',
          'value'   => ''
        )
      )
    )
  )
));