Is it in yet?  Need garage parking clearance sensor with display design

Hi Dave,

Detecting a light emitter from across your garage door can be a bit of a hassle, mostly because you have to compete with the giant burning emitter in the sky.  Correctly biasing your detector might actually be impossible, given the ultra-wide range of ambient light conditions you'll be fighting. Most new garage door openers that come with a safety beam system use lenses and filters to block out all but the light they're interested in. It's not impossible, just a hassle.

Another possibility is doing it farther inside the garage.  You could detect when a beam is broken by the front bumper and turn a light on.  Alternatively, you could use an ultrasonic range sensor on the back wall of the garage to detect the distance to your front bumper. When the distance crosses a set threshold, it turns a light on.

...or, the easiest option:

Here's another distinctively non-tech solution:  Mount a wide-angle mirror (can obtain at any auto parts store or the big W) on the back wall of your garage at the height of the center of your vehicle's rear window.  The driver can see the mirror when pulling in either way, and in the mirror you can see the remaining distance between bumper and wall.  Could also align it with the side of the vehicle, rather than dead-center, to allow seeing brake/backup lights or headlight in the mirror.  Could alternately use a regular (non-wide-angle) mirror and angle it such that once the vehicle appears in the mirror, the vehicle is at the correct distance from the wall (so that you don't have to identify both the vehicle and the wall in the mirror, which could be challenging if the mirror is small).

I know it's a bit late, but I just found a project that an EE built so that he can open and close his garage door with Siri:

http://hackaday.com/2012/12/11/garage-door-opener-using-siri-and-raspberry-pi/

Pretty neat!