I love arguing about irony with my students. They always mix up real irony with mere coincidence. Although irony in literature is fun, I love real world irony even more.
Here's a situation that skirts the boundary between irony and coincidence:
John Joseph Adams was a sponsor of the zombie caption contest over at Tor.com. On the day I found out I had won, I received a rejection in the mail from Fantasy and Science Fiction signed by John Joseph Adams.
Now if that doesn't put the universe in balance, I don't know what does. Is it ironic? Go ask Alanis Morissette; I'm too tired.