The ban, where it exists, is generally ignored, yes. And a nation-wide ban will have the same fate, at least eventually. It's really a lot like Prohibition: all you're going to accomplish is turn otherwise law-abiding citizens into willful criminals (a common ploy of fascist states I might add).
I'm not arguing that cell phones are not a distraction, but that it's a symptom and not the disease. The real problem is a lack of attention to their driving and I see examples of it every day on my commute (the worst of which, IMHO, is makeup application at 90mph).