I have these line in my wp-config.php to dynamically set the blog URL based on the http request.
define('WP_SITEURL', 'http://' . $_SERVER['HTTP_HOST'] ); define('WP_HOME', 'http://' . $_SERVER['HTTP_HOST'] );
The purpose of this is to enable a staging server... whatever URL you use to connect to the site, all the links to stylesheets etc will be to the same server.
A recent update to WP Super Cache broke this. It's the CDN functionality. The CDN assumes that it knows your site URL. Also it is turned on by default.
Setting the CDN include_dirs to a nonsense value is a good workaround. I'm not sure what the best fix would be... Not enabling CDN support by default would be a good start, and having a checkbox to enable it in the settings.