Unless you live far enough away that your neighbours won't hear, I'm going with rude. Honking the horn if there's some sort of danger is fine but otherwise? Waving achieves the same result (says goodbye folks) without disturbing the whole neighbourhood. This would get on my nerves if the honker was a frequent visitor.
I live across the road from a small suburban shopping centre (a chemist, doctors' office, newsagent, grocer's, bakery and hairdresser's). It's smack in the middle of a residential area - several townhouses, units and single dwellings. I've noticed a lot of people seem to think standing on the horn is the best way to hurry up their other half (or whichever passenger is shopping). It always seems rude to me, although perhaps inconsiderate is a more accurate description.