Photographer Dennis Rito has used this global phenomena to create a set of wonderful portraits of people texting on their cellphones. Called Unlimitxt it is well worth looking at. Though still a work in progress the level of concentration depicted and the broad collection of all types of people involved in this now common task is amazing.
In Japan (as above) texting is not popular; most people use their phones to email each other (which sort of amounts to the same thing). But the mobile phone itself is ubiquitous, always open, always being read, scanned and used for an ever increasing number of purposes. Amazing really when you consider a mere 10 or 15 years ago almost no-one had one. Now we cannot live without them.