BTW, a bit OT but relevant to some comments here, there was a study made a year or two ago that concluded that people get angry about mobile phone conversation not because it is too loud or has annoying content (substitution with two people talking at the same level and same content did not trigger the same response). The study concluded that what drove people nuts is the fact that they only heard one part of the conversation and sub-consciously felt excluded.

Something to think about when you get that urge to grapple the mobile phone out of the person next to you and throw it out of the window. It isn't them, it is you.