I dont coz mine are confined to the house and my garden but for free roaming kitties I think I would.
My friend has just taken in a ?3-4month old kitty she found sitting in the middle of the road without a collar. She was worried about traffic but although he might be chipped she has no way of knowing. She is putting up posters to say she has found him but it could of saved his owners (presuming he has any) alot of stress if he had an address attached..
Oh and dont worry if no one comes forward he will be off to the vet for a quick scan!!