ref. http://arduino.cc/forum/index.php/topic,42489.0.html

const int button = 3;
const int led = 13;

int bounceTime = 50;
int holdTime = 250;
int doubleTime = 500;

int lastReading = LOW;
int hold = 0;
int single = 0;
int LEDstate = 0;

long onTime = 0;
long lastSwitchTime = 0;

void setup() {
  pinMode(button, INPUT);
  pinMode(led, OUTPUT);
  digitalWrite(led, LOW);
  Serial.begin(9600);
}

void loop() {

  int reading = digitalRead(button);

//first pressed
  if (reading == HIGH && lastReading == LOW) {
    onTime = millis();
  }

//held
  if (reading == HIGH && lastReading == HIGH) {
    if ((millis() - onTime) > holdTime) {
      invertLED();  
      hold = 1;
    }
  }

//released
  if (reading == LOW && lastReading == HIGH) {
    if (((millis() - onTime) > bounceTime) && hold != 1) {
      onRelease();
    }
    if (hold == 1) {
      Serial.println("held");
      digitalWrite(led, LEDstate);
      hold = 0;
    }   
  }
  lastReading = reading;

  if (single == 1 && (millis() - lastSwitchTime) > doubleTime) {
    Serial.println("single press");
    single = 0;
  }

}

void onRelease() {

  if ((millis() - lastSwitchTime) >= doubleTime) {
    single = 1;
    lastSwitchTime = millis();
    return;
  }  

  if ((millis() - lastSwitchTime) < doubleTime) {
    toggleLED();
    Serial.println("double press");
    single = 0;
    lastSwitchTime = millis();
  }  

}

void toggleLED() {
  if (LEDstate == 0) {
    LEDstate = 1;
  } else {
    LEDstate = 0;
  }
  digitalWrite(led, LEDstate);  
} 

void invertLED() {
  if (LEDstate == 0) {
  digitalWrite(led, 1);
  } else {
  digitalWrite(led, 0);
  }
}

ref. http://www.arduino.cc/playground/Code/Button
Arduino Button libraries 에
onPress(), onDoubleClick(), isHold() 메소드가 있지만
아직은 불안전하다.