We've lived in many a house where the pizza delivery guy couldn't figure out which house was ours (before we learned how to make killer pizza at home). Making our house numbers or mailbox a bit more reflective could have helped them out! It does say on Rustoleum's website that it's able to be used on metal, wood, plastic, concrete or masonrys, so your curb might be an option, but we haven't seen the results of this application yet!
We also think it could be a great thing to add to your bikes, lawn mowers or anything else that might be used as the sun is setting. Spraying a coat onto your favorite shovel or pair of shears might help locate them on those long days where you try to spend every moment you can working on your outdoor spaces. We've had to leave many a gardening tool outside over night after having set it down and not being able to find it until morning!