Looks like they've updated their sheets based on "real-world" experience over time, as has been covered extensively here now, these Cree's seem to "burn-in" and actually settle in a bit better in the Vf curve over time, hence better efficiency, and now that half a year has gone by, with many 1A applications without reports of much/any problems in the field (and one would assume they've had "production" models now running long-term testing in their labs), they've probably concluded that they can safely extend the originally conservative specs a bit further. Imagine a car maker building an engine, testing it some in the lab, and the material engineers say "we are 100% confident this engine can handle 6000RPM sustained"... so the initial spec will be 6k... but after 6 months of production and sample testing, at extended RPMs above 6000 (say 6200), and no red flags, they might bump the spec up to 6200. Maybe the engine/LED can run fine even higher than that, but for now, they manufacturer is expressing confidence up to that level.
Also remember that this is assuming all other parameters are within "design specs", the 1A operation still depends on proper heatsinking, etc, so if you have a .7A light that works fine, and bump it to 1A, it doesnt' mean you won't have a problem, because if you are at the limit at the 0.7A, you will still be "above spec" at 1A. A Corvette might be rated at a top-speed of 162MPH, but if you go 162MPH on Wal-Mart economy gas-miser touring tires on there, you are going to have serious problems.