First, we need to understand what a splog is. Essentially, it is nothing more than a bot that creates “junk” blogs and embeds links to the splogger’s main site, usually for no other reason than to increase its page rank through trackbacks. They usually seek out the wp-signup.php page that is present in every default WPMU installation. One could simply change the name of the file to something like registration.php and make corresponding changes to all of the references to wp-signup.php in all of the themes used. While effective, this was not the best course of action for me, considering all of the themes used on my blogs. Instead, I dug a little deeper and found some interesting info.