Fifteen years ago I went to Australia, and was astonished at how many people were using mobile telephones -- all we had in San Francisco was the rare in-car brick phone.
It took Silicon Valley a good couple of years to catch up in mobile telephony.
Eight years ago I first went to Japan, and was astonished at how many people were looking at their hands, not holding their hands up to their ears. Although San Francisco had a few Blackberries and Palms back then, it wasnt´until the iPhone craze that we saw people bumping into things on the sidewalk because they thought they could multitask while staring at their hands.
Once again, San Francisco lagged behind global trends.
Here in Hong Kong in 2009, itś very striking how many people are using integrated earpieces, holding conversations while walking down the street. They may bump into things, but at least their eyes are often up, out of their hands. You have to doublecheck whether theyŕe talking to you, or whether theyŕe talking to someone you can´t see.
In this, at least, San Francisco is finally ahead of the curve.... ;-)