Note: '07 model shown). Whether or not it will be standard equipment is unknown at this time, but look for it to be available one way or another. It's worth noting that the new Toyota Tundra has an available six-speed as well, so it seems like a natural choice for Ford to offer one, as well. In addition to simply matching up with Toyota, the additional fuel economy the extra gears offer shouldn't be ignored. Six-speeds are available for the large SUVs from Ford and GM already, so the appearance of one on the next F-150 seems like a completely natural progression to us. Truth is, given that six-speed transmissions are becoming more commonplace in a variety of vehicle types, it probably would have been more of a surprise to hear that Ford wasn't going to offer one.
[Source: Automotive News (sub req'd)]
Automotive News is reporting that the next-gen Ford F-150 will get a six-speed transmission (