If you ever intend on taking down your gwebcache site, it's a bad idea to put it up, as can be read about here.
http://www.c0re.net/gnuforum/viewtop...asc&highlight=
I've had mine down for over 2 years and a quick grep of my access logs reveal that there have had 343,141 hits on one site since December 2003.
There is no clear cut way to get out of the cache system, and no amount of 404 error codes will discourage certain apps from using your url.
Yeah it's great at first, but if you need to move it for any reason, or remove it for any reason, you're locked in to that traffic no matter what.