It couldn't hurt. That is assuming you really don't have problems with emergency or ER personnel digging around your stuff and you don't keep sensitive information, unencrypted sensitive information, on your phone. I don't so at worse it is a waste of effort and they never see it or do anything with it.

On the other hand ... If your comfortable with people seeing the contents of your phone, perhaps you encrypted the sensitive material, and things go your way it might save a lot of time. It could, conceivably, save your life.

So this is a good tip in my book.

On many phones it is possible to change the display shown when you open it to display a few lines of text. A friend has his set to tell him to "Bear Down", a popular saying in the financial circles he travels in. I see no reason why you couldn't substitute a line the showed "ICE" and an emergency number.

Of course the contact list and speed-dial lists would also be good but the person would have to dig a bit.