Yeah, I think a few of us have seen this before, stales, it's pretty funny nonetheless. The irony refered to is of course the simplest flavour, and perhaps the most common which is virtually indistinguishable from sarcasm.
I read recently that sarcasm derives from a term that means 'to tear the flesh' - and is thus thought a more course and crude version of this irony, although the terms are often used interchangeably. Dr. Johnson said something about irony being a mode of speech in which the meaning is contrary to the words. This must be seen of a scale though - most uses are not necessarily diametrically opposed. Sarcasm on the other hand is pretty black and white.