Links to Nuvole site and feed in Drupal Planet point at drupal.org

I tried to fix it by editing the aggregator item and saving it, but that didn't help to fix it.

I'm not sure what's going on, but this is apparently a bug with the core aggregator module (and maybe something about our infrastructure?) so I guess I suggest you hunt for bugs in the core aggregator module.

I think the problem is the following function (aggregator.pages.inc):

function template_preprocess_aggregator_feed_source(&$variables) {
  $feed = $variables['feed'];

  $variables['source_icon'] = theme('feed_icon', $feed->url, t('!title feed', array('!title' => $feed->title)));
  $variables['source_image'] = $feed->image;
  $variables['source_description'] = aggregator_filter_xss($feed->description);
  $variables['source_url'] = check_url(url($feed->link, array('absolute' => TRUE)));

  if ($feed->checked) {
    $variables['last_checked'] = t('@time ago', array('@time' => format_interval(time() - $feed->checked)));
  }
  else {
    $variables['last_checked'] = t('never');
  }

  if (user_access('administer news feeds')) {
    $variables['last_checked'] = l($variables['last_checked'], 'admin/content/aggregator');
  }
}

What is reported as URL is taken from $feed->link, but as far as I can see, that field is not present in the form to add new feeds to the aggregator, nor is it saved in the database.
In that case, the value returned by check_url(url($feed->link, array('absolute' => TRUE))) can only be a link to drupal.org.

Now the URL is correct. I don't know if somebody fixed it, or something else happened.