Anti trackback-spam module for Drupal

The patch is working quite nicely for me - in 12 weeks, only one spammer got through (and ended very quickly on my blacklist). So I extracted my code into a separate module, reducing the size of the patch for the original multiping module.
You can get it on my Drupal page. Don't forget: It is not enough to install the module, you have to apply the patch included to the original trackback module.