I downloaded Flashlight: http://maemo.org/downloads/product/M...hlight-applet/

Is it safe to keep this on for a long time? Do they over heat or do the bulbs die quickly?

for the led is not a problem to stay on for a long time but i don't know if is ok for driving asic. if the asic disipate some power it may overheat and possibly burn ( this asic can drive high current but i am not shure for heat ) and led will drain your battery quickly ( i asume leds are 1-3 W rating so totaly 2-6 Watts is too much for a battery capable of 6 Wh
i use flash for short time ( minutes )

LEDs are known for their longevity. However, it is a drain on your battery, so I highly recommend that you use it only when necessary.

FWIW, when the LED flashlight app came out for the Droid, I performed a battery drain test, and ran the light for about 2.5 hours, before my battery changed (1) increment from full. The LEDs were cool to the touch.

short answer: it's safe
see: http://talk.maemo.org/showthread.php?p=482124

These LED's aren't driven hard enough to generate a lot of heat in torch mode.

Found the previous thread with more info.
Check out my posts. 1 in the middle and 1 at the end.

http://talk.maemo.org/showthread.php?t=38223