I catch the irony, but I'm not confident that it really contributes to the discussion here. Look at the comment thread it's produced: practically nothing of any consequence or interest.
Sarcasm is a form of irony - one meaning of irony is saying one thing, and meaning another. "Sure, that's a great idea" is both sarcastic and ironic (although not ironic in the sense people most commonly use the word, which non-ironically, is not that ironic).