Key_Master - 10:57 pm on Mar 6, 2012 (gmt 0)
The original IP requesting the content from your server isn't exactly hidden. YahooCacheMobile uses the X-Forwarded-For header:
Lots of mobile phone carriers use proxies. Almost all of them will forward the original IP using the same header. I use Opera Mini and Blackberry browsers. Both port my carrier's IP through a proxy.