OH dear here we go ...again
Sorry to put you out so much. My 4S is new and my first iPhone. I bought it unlocked in the US, but Apple Mexico has no trouble working with me on an issue I had with the local carrier that I am using. That sounds like a world-wide warranty situation to me.
My sister, the lawyer in our firm, and I have read the warranty link that you provided. We find nothing in the pdf to suggest that the Apple Warranty is not world wide. There is the clause that Apple may restrict the warranty to country of purchase. May being the operative word. In my experience, Apple has honored the warranty world-wide for many years, except in unusual circumstances, such as the Verizon specific iPhone and iPad. Those are warranted in the US only because the parts for them are not supplied by Apple in its supply chain world-wide. My personal experience with many Apple products, including my new 4S, is that Apple honors its warranty world-wide.
Unless you have a direct experiene with Apple warranties not honored world-wide or can point us to specific language from Apple that the warranty is only honored in the nation of purchase, then I believe that your opinion is inacurate and perhaps best not published as factually true.