The way to get around the "at least four character" search constraint in the forums is to use Google to do the search. I remember reading the LED brightness posting you mentioned. I went to Google and entered "netduino pwm" as my search. The first few hits were in the Netduino Forums and the second one was exactly the posting you referred to.Use a PWM. You can then control the brightness by changing the duty cycle (duration). I would reference the articles in this forum but you can't search for PWM or LED because of the search rules
Paul