Cutting out of another idea, I'll edit to clear up at somepoint hopefully.
Anyways I'm jumping on as you say
'Garage door open'.
Now what would be ace if the phone used location awareness like my Wave heating controller
Basically using GPS on the phone with the app to know you location, set the pin on Google maps to where you would like your 'centre to then be' from where it thinks you are.
Then if you leave the area of the house/leave the house.
You can then set a distance from this location (can't rember if Wave does this or it's a default reasonable distance given GPS accuracy and search period)
It then sees if the phone is in/out of that circle and triggers your alarms. Which we can define a triggee, like rub throughs door open, turn hearing down, lights left on, turn these lights off. Etc.
I guess thinking about it turn the Android phone into a cayenne device and add it to the Internet of things, not just a controller.