Just to finish this up...
Here's a youtube link to the actual lightbot/ light activated solenoid:
This was my first arduino project.
It is really a combination of 3 smaller beginner tasks:
blink an LED
Use of a photoresistor
Control a motor or solenoid with a mosfet transistor
I combined all 3 to fix an annoying problem at work: The building control system turns out the lights at 6 or 7 pm but we stay til 1am.