There is the thought-dulling sarcasm common on the internet that is equivalent to preaching to the choir in reverse, "It's ok, congress is on it" or "Another cold day, so much for global warming." Similar is the the teenager's use of mocking sarcasm as a blunt act of defiance.
Then there is the playful language that makes the listener try to inhabit the mind of the speaker and likely does generate creative thought, such as the article's example “Pat, don’t work so hard!”
Finally, sarcasm can be used to express ideas that, if said bluntly, would be unacceptable. A boss can tell a recently-berated employee, "the customer is always right" as a way of commiserating with the employee without directly discrediting the customer. Or a coworker can say "Another good policy decision from management" and gauge the listener's reaction without directly revealing their own opinion.
Pinker on shared vs mutual knowledge, the value of ambiguity: http://scholar.harvard.edu/files/pinker/files/evolutionary_s...