Through September 15, 2014, you will get a 25% bonus when you transfer your American Express Membership Reward points to JetBlue.
Typically the transfer ratio is 250 Membership Reward points = 200 TrueBlue points, however, with this 25% bonus, you’ll get an extra 50 points, so 250 Membership Reward points = 250 TrueBlue points. This gives you a 1:1 transfer ratio which is on par with the other airline partners.
While a 1:1 transfer ratio is great, keep in mind that JetBlue has a semi fixed value when you go to redeem their points. Overall, you get an average of 1.5 cents per point (although can be as low as 1 cent/point, and as high as 1.8 cents/point). So before you transfer your points over, see the value that you will receive on your desired flight and determine whether or not that is a rate that you like to redeem your Membership Reward points for. I personally like to get at least 2 cents per point with this currently (which I can get when transferring to British Airways Avios points), but if you are looking to get rid of your points and you typically don’t redeem for that high of a value this could be a good option.
Remember, JetBlue also allows families to pool their points (related post), so this could be an option to transfer points from multiple Amex Membership Reward accounts.