OK I'm a noob hack, but I finally got my Arduino to respond to light.

Here's the code, note it's not much changed from the  AnalogInput example.  Actually I'm not sure I ended up changing the sample at all, just used a photoresistor from +5V over to analog 2 along w/ a 1k resistor to ground.    

/*
 * AnalogInput
 * by DojoDave <http://www.0j0.org>
 *
 * Turns on and off a light emitting diode(LED) connected to digital 
 * pin 13. The amount of time the LED will be on and off depends on
 * the value obtained by analogRead(). In the easiest case we connect
 * a potentiometer to analog pin 2.
 *
 * http://www.arduino.cc/en/Tutorial/AnalogInput
 */

int potPin = 2;    // select the input pin for the potentiometer
int ledPin = 13;   // select the pin for the LED
int val = 0;       // variable to store the value coming from the sensor

void setup() {
  pinMode(ledPin, OUTPUT);  // declare the ledPin as an OUTPUT
}

void loop() {
  val = analogRead(potPin);    // read the value from the sensor
  digitalWrite(ledPin, HIGH);  // turn the ledPin on
  delay(val);                  // stop the program for some time
  digitalWrite(ledPin, LOW);   // turn the ledPin off
  delay(val);                  // stop the program for some time
}

Video's not very good, but you'll get the idea.  

ArduinoBlinky.wmv (5.49 mb)