(keitai-l) keitai etiquette?

Thanks for all the responses about email vs. SMS. I guess it was more involved 
than I thought. I was also wondering about keitai etiquette. Obviously 
regulations say you can't talk on the trains, but I was wondering what it took 
to get to that point since I read about a time when it was a problem. Were 
there protests? Angry letters to the train company? Is it still considered a 
problem in other public places like restaurants or theatres or libraries or has 
texting become so predominant there's no need for regulation in these spaces? 
Are there any rules about keitai use while driving?
Thanks
Marcela