Interesting quote here from The Economist, April 12th 2008, regarding the tendency for young Japanese to use their mobile phones in new ways to stay in touch:

" ... entire cliques do this sort of thing, creating, in effect, their own tribal medium and narrative.  Ms Ito [an anthropologist, researching the subject] has noticed a new genre of photography on the rise as young people use their phones to snap photos of everyday situations – the view from the escalator on the way to school, say – which mean a lot to their friends and nothing to anybody else.  They especially love photos that capture "dumb things that their friends do", such as getting drunk and falling into puddles, which collectively amount to "everyday, casual documentaries" for a circle of friends."

I am not sure how "new" this particular genre of photography is – people have been taking cherished photos of seemingly mind-numbingly innocuous scenes for generations.  You can come and sit through my last set of family holiday snaps to get that point.