Unless Google's cache relies on loading content from -opensocial.googleusercontent.com domains?
I'll inform Hubird about this as I don't have an example where this whitelist is triggered.
Bear in mind that I wrote that rule not knowing the initial purpose of the whitelist. I had assumed it was to avoid breaking Google Docs (has happened to me before without a whitelist like this). My main concern here is that whitelisting anything on entire of googleusercontent.com is effectiely whitelisting it on the entire Internet for anyone who uses Google's webcache.
When I initially added the rule I made a not in the Antisocial list saying the filter should be removed if it gets hits anywhere other than on Google services.
The rule is less than ideal and if someone can come up with a better rule I'm open to suggestions
Going to http://www.google.com/ig?hl=en with the exception rule enabled, I did not find "webcache.googleusercontent.com" in the blockable items list, so I don't think this rule switch would cause any issues on that page?
I don't have an example off the top of my head but here is how to get one: Find a site that is not google that loads something from a -opensocial.googleusercontent.com domain, then go to that website through Google's cache. I am guessing that you might know some examples of such sites given the blocking filter for -opensocial.googleusercontent.com on non-Google domains?