Drupal 7 custom form date_popup element
Custom datepicker options are now supported (as of Date module version 7.x-2.6) by setting the necessary values with #datepicker_options. Alex's use case of a custom form element to display only future dates would look like this:

$form['date'] = array(
  '#prefix'=&gt;t('When do you want to start the featured campaign?'),
  '#date_format' =&gt; 'Y-m-d',
  '#date_year_range' =&gt; '0:+1',
  '#type' =&gt; 'date_popup',
  '#weight'=&gt;0,
  '#datepicker_options' =&gt; array('minDate' =&gt; 0),
);