The Singular 'They'
Linguistics specialist Henry Churchyard has an interesting discussion about why the singular "they" is correct in many cases and has a long and honored history.
Check it out.
Given that "they" is pretty much ingrained into speech, this could be a useful reference. But as he and others point out, it's still incorrect to use "they" to refer to a specific antecedent. So no "City Council said they " or "At Bongoville Chevy, they ..."
Thanks to a former student, Corey Garriott, for the outpoint.