If I put the IP address of a foreign Google datacenter, will I get to see the search-results shown to people in that country? We're pretty certain we have some local competition in the UK, but since we're not seeing much in the PPC or the organic (we've tried easy things like changing TLD and specifying "results in the UK"). Of course, this would help with our other foreign sites, too ...

I remember this being discussed before, but I can't seem to find it.

It looks like the "gl" parameter will also adjust the ads. For example:

US: http://www.google.com/search?q=cars&gl=us
UK: http://www.google.com/search?q=cars&gl=uk
or: http://www.google.com/search?q=cars&gl=gb

(Note: Testing this from the US, it seems you can use either "uk" or "gb" for the UK.)