I hate that damn light too!
I too would like to be able to adjust the pulse rate of the power button on my monitor and tower as well. I love darkness when I'm trying to get a sleep and have covered up LED's on my zip drive, phone, iSub, and even put tint on my alarm clock to keep the light level as low as possible.
However, the worst offender is by far my G4 and the monitor.
The advice some people here have offered doesn't really work:
1) Tape up the button
Normaly this would work, but the plastic of the monitor and tower reflects & refracts the light so you have to plaster the enitre front of the monitor and tower face (mines an older Gigabit? G4) with tape. The result is one fugly looking set up and a tiny glow coming from the bottom right corner of the monitor... and I'm not taping up the screen!
2) Cover it with something.
Now I've had varing degrees of success with this. For my Tibook I have an old scarf that I cover the back up with and that works. Using a t-shirt over the monitor and tower works ok, but I still get light leaking around (or through) the shirt. Puting cardboard or the like is even worse, I have my monitor right up against the wall and the light simply reflects off the cardboard and onto the wall making appear brighter than before. Also unless you have a fitted piece of cardboard for your tower, the reflection from that gap is even worse than the monitor! BTW I should also mention this makes your computer look fugly or make you look like a slob.
3)Open up your computer and take out the LED.
Well this one would work, but you got to know what your doing. I aslo wonder that if you did this would the power button still work like it used to? Futhermore I've got a 17" ADC CRT monitor there is some serious shock hazzards when opening up those things.
4) Turn it off.
Well this is what I do, but some may want/need their computer on. It's my understanding that there are some scheduled repairs and checks that a computer will run late at night and if your computer is off they don't get done. I'm not sure if it's affected my computer's performance any, but I sure can't brag about my uptime.
Since the pulse rate is something that runs even when the disks and computer is asleep, I'm assuming that any modification to the pulse rate would be a firmware hack. I have yet to run accross anyone who is skilled enough to pull it off. And I doubt apple would give users the ability to play with firmware settings from the OS.