I only think it's annoying when they should be putting their shit on the counter and instead do it at half speed and take forever to pay.

One day there will be a device the size of a hearing aid, controlled by thinking, which works as a computer headset, hands-free cell phone, mp3 player, and digital radio, all in one.

They managed to control the new iPod shuffle with only 1 button, plus 2 for volume. Distinguishing between 3-4 different signals in a brain-computer interface is already old technology.

In my observations people on cell-phones tend to lose all awareness of things around them. When talking to another person they're forced to extend their zone of awareness beyond a small object they're pressing against their ear. Furthermore when someone is actually there in person they're far more likely to put the conversation on hold while they attend to something important that needs more of their attention, I almost never see someone on a cellphone do this. There's also the whole things where they speak at a volume 4 times louder than necessary.

So its not that they're talking on the phone, its that by in large many people seem to be completely unable to do it in a responsible fashion.