Pratt has been doing ground tests on the engine, and it is expected to bolt one on to the wing of its testbed 747 in the middle of the year. Well now the company is also saying that it will be testing the GTF on the wing of the Airbus A340 testbed. This is really interesting because Airbus has no plans to use this engine . . . yet.
If things go well, Airbus may have a leg up on Boeing in developing its next-generation narrowbody. Then again, that's a big "if." My understanding of the GTF is that it's a pretty simple idea. Currently, all stages of jet engines turn at the same speed. The GTF would use gears to allow each stage to turn at the speed that's optimal for it. This means that the big fan on the outside will be able to turn slower while the turbines on the inside will speed up. That will result in better fuel consumption and lower noise.
But while the idea may be simple, the implementation is complex. These geared systems can be tough to get to work right, and apparently there hasn't been much luck with them in the past. Boeing has shied away from the idea previously, but now Airbus is at least sniffing around. It will be very interesting to see where this goes. It could be a spectacular success or a terrible failure (Rolls-Royce RB211-style). It's a big gamble but it may very well pay off.