Writing in public places has had a long tradition, writes Conor Friedersdorf, but the advent of laptops has made this the era of coffee shop telecommuting. Friedersdorf thinks that is the level of distraction in restaurants that is just right to keep the brain from freezing up:
"Put in a silent room before a blank page, it's almost impossible to write. Neither is it be ideal to work near a television set that keeps drawing one's attention or a room where a child keeps interrupting. In a coffeehouse, its rare for someone to intrude on the space of a patron with an open laptop and a look of concentration. Still, there is just enough conversation and foot traffic in the background that you're forced to semi-consciously tune it out."
The article highlights a handful of other explanations for the phenomenon.