It will not have escaped your notice that the concept of irony has degraded into something that ... well ... to an extent actually defies definition or explanation. Modern irony is a beast that refuses to die and both the UK and the US is to blame in at least equal quantity.
For example, it seems to me that a lot of British people like to accuse the American people of not understanding the "concept of irony". While I can't confirm or deny this slur, when pushed for examples and explanation, it appears that what these British people are actually trying to accuse them of, is not understanding sarcasm. Sarcasm is not directly or necessarily irony (as you are of course aware). And definitely vice-versa. Please see the following page regarding Sarcasm and its place in the whole story. See more about sarcasm and examples here.
Metafiction, sometimes better known as Romantic irony (the 'Roman' part, I'm informed, is due to the Romans being the guys behind it, not 'romance', is when authors purposefully and consciously draw the readers' attention to the fact that you're reading fiction, reading a story, that the author knows you are there and addresses you directly, pointing out the fiction. The simplest examples of this are found in the interjections of an author as narrator, giving you little tidbits of information or ideas about what's going on in the author's mind, or beyond the written story.