I think it's ridiculous when people claim to be offended when something relates to them, yet will happily enjoy something that is offensive to others.
My friend has a theory that people are rarely actually offended, just like to excercise their right to be offended and he's definately onto something. Australia was the butt of many many jokes in that particular episode, as I bet the British will be in the Australian version of the show but I couldn't care less.
Do you really think that the Mexican people could care less about what was said? I have a Mexican friend who thought it was hilarious. People need to chill out, of course it wasn't xenophobic, it was a joke...