Red_Avatar: Meh, not impressed. It's basically an algorithm that looks for certain phrases & punctuation. I think if they had tried this on the British Amazon, the results would have been a lot lower. Americans tend to make REALLY obvious sarcastic comments using exclamation marks, classic sentence structures (like "Gee, I sure like ... ") and, just in case you didn't get it was sarcasm, mention it just in case (*sarcastic voice*). Brits use a dryer form of sarcasm that is a lot harder to detect.
I think drier sarcasm is easier in some societies. I used to be very dry in my sarcasm until I got my current job; too many people thought I seriously meant the things I said.
I do question whether this can be done successfully by software. In the place and time I grew up, I was taught that "sir" and "ma'am" were how one addresses people with respect and in formal situations like doing business or with someone you don't know well. In other parts of the country, people get offended because it almost always used sarcastically. How is a program going to account for place and time like that?