My passport was to expire 4 months from my return date on my Dec 31-Jan 10 trip. I thought I was good, however a week or so before leaving, I saw a Facebook post about it. Several wrote that the policy has changed and it's now 6 months. I called the Jamaican High Commission in Canada to ask, and was told I'd "probably" be ok, but it is now 6 months. I decided not to risk "probably" and got a rush renewal. Ended up using Mobay arrivals and my rep took me right past customs, didn't talk to an agent, and used the kiosk at immigration. May have gotten away without 6 months validity, but it seems it would be taking a risk. US citizens, it seems mandatory from the U.S. end, as well as the "official" Jamaican end.