It is actually pretty common to hear this called an Anolrd Palmer in most parts of the country. It is also sometimes refered to as a half and half.
Arnold Palmer (as local legend has it) used to order a cold drink of half iced tea, half lemonade at the country club after golfing. That combination is well known in Pittsburgh, PA and surrounding areas (which would include Latrobe, his hometown) as an "Arnold Palmer."
Does any one know why Arnold Palmer's name is attached to this?