This is one of the most unusual promotions I've ever seen. Basically, this is the way it works: If you buy a JetBlue all-you-can-jet pass for $599 between now and Aug. 21 you can fly anywhere the airline goes virtually as often as you'd like from Sept. 8 to Oct. 8. And there are no blackout dates.
There are, however, restrictions: Flights must be booked no later than 1:59 a.m. EDT three days before the flight's scheduled departure. Tickets are nonrefundable and nontransferable. And taxes and fees for international and Puerto Rican flights are not included. The rest of the fine print is here, but given the breadth of this sale it still looks like a pretty good deal.
If you are interested, you should jump on this, as the airline points out that the passes will be available till Aug. 21 "or while supplies last,'' which suggests that it if there is heavy demand JetBlue could halt the promotion early.