Christian has previously stated that the one hour of runtime at maximum brightness (500 lumens) is for a continuous light level and does not include any time once the brightness begins to degrade due to the battery level. That means the flashlight with the included 2400 mAh battery SHOULD last for one hour on maximum AND STILL BE 500 lumens.
Flashlights with battery life levels measured with ANSI FL1 are nothing like this. The ANSI FL1 standard measures the amount of time from 30 seconds after the flashlight has been turned on until the beam has degraded to 10% brightness.
I don't have any data nor do I have a way to measure to ANSI FL1 standards, but I have a feeling the HexBright would be more around 1:20 or 1:30 maximum setting battery life if it were measured to 10% of original brightness per ANSI FL1.
You must keep in mind the HexBright has a lot of additional electronics that most flashlights do not that also reduce battery life.
Christian has also mentioned he intended the LED to be replacable when more efficient LEDs come out. The HexBright is current limited to 1.6 amps, so you will not be able to increase brightness without replacing the LED with one more efficient. As for increasing battery life, well, I put an Orbtronic 3400 mAh battery into mine and per calculations I should have 85 or so minutes of 500 lumen brightness on maximum (not tested).
This shows what I was referring to. The specific flashlight you linked from Thinkgeek only shines the advertised 860 lumens for, well, almost no time at all. After approximately 7 minutes it drops to ~650 lumens. After 21 minutes, it drops to ~465 lumens and stays there until it begins to degrade. As you can see by the various degredation graphs of the different batteries that once it begins to degrade, it can still last a long time increasing an already inflated runtime. If this flashlight were to stay at 860 lumens for the entire duration, you can be assured the runtime would be MUCH SHORTER.
This second graph is on the high setting, ~515 lumens (similar to the advertised HexBright maximum setting). The different batteries get 55, 84, and 96 minutes before any degredation occurs. That is data that IS directly comparable to the HexBright's advertised 60 minutes on high (Although the 2600 and 3000 mAh batteries are a higher rated capacity than the included 2400 mAh with the hexbright).