agent_x - 10:17 am on Dec 9, 2011 (gmt 0)
This phrase can mean just about anything. I went back to check because I remember seeing it recently and it definitely isn't anything to do with scripts!
It shows the location Googlebot was at before it was redirected to land on your page, so it could be the non-www version of your page before your .htaccess redirects it to the www version for example. But in the context of this thread, it's the location of the redirect script that does a 301 or 302 redirect to your page.