An incubator is really meant for poultry like chickens and the others that have young that have fuzz on them and can eat and feed themselves. Parrot people use them to hand raise, but that really is a specialty for professionals. I don't recommend anyone hatch a pigeon's egg. It is a rare occassion that someone would have an incubator set up and running without eggs in it, and then the next day they find a pigeon egg abandoned or needs to be saved. So I would'nt put any ideas into their heads to go out and buy one and then go get a pigeon egg and try to hatch it, not thats what your were trying to say, just some will go ummm I might want to try that...I agree with Spirit wings, in order to hatch eggs successfully it takes a highly monitored specially built egg incubator. The humidity and temperature needs to be just right and they need to be turned frequently to prevent the foetus from being "stuck" at one side of the shell.
Then, if or when they hatch, they need to be fed at least every half hour during the day light hours, take alot of attention. Finally when they've grown up, they need to be taught what to eat and how to fly.
Its something definately best left for the parents.
If for any reason you've found eggs which have definately been abandoned, a cat/crow has taken the hen, the nest has been destroyed etc, then you could try hatching them, it depends on how old they already are, if they've just been laid-say 0-1week old, they probably wont hatch as its going to take some time to reach their hatching date and having them in the airing cupboard just wont do it. If they are real close or on their hatching date, they may hatch they may not, but again, you really need a professional egg incubator.
Eggs are incredibly difficult to hatch, its amazing how the parent birds do it.