Typical LEDs have a light efficiency of about 25 percent. Newer technology is better, but generally, that's it.

I have a lighting system at home that is custom made, featuring CREE's latest and trust me, they need large heat sinks, air flow and care. Overall, the best of them dissipate at least a quarter of pumped power in heat.

Stats vary because after a certain level the power-to-light ratio goes through the roof. Lighting systems usually are close to this limit, it's a balance between efficiency and lifetime.

I very much doubt any LED system dissipates less that 25 percent, in a lighting solution, like N900's flash. As a result, we're looking at some heat, and, not dissipated, it will heat the base and cause it to dim.

So, not only they DO heat, the first sign you are in trouble is that the light DIMS, not burns out. After 15 minutes, it could still work but only put out 80 percent the light it used to.

I usually use the backlight for the LCD for light, at least they have heat sinks, are not clumped together and have been designed to stay on for a long time.

Use a blank image of a blank browser page, crank backlight to max and enjoy.