The act of walking slowly or "shuffling" because you're too preoccupied with tasks being done on your smartphone such as browsing the internet, texting, etc.

The Smartphone Shuffle can sometimes be dangerous for oneself, such as crossing a roads, not paying attention to surroundings. It can also be a nuisance for other people as distracted Smartphone Shufflers block hallways, stairs or sidewalks and impede flow of pedestrian.
Stop doing the Smartphone Shuffle! You're blocking the sidewalk.
by Ronnie J January 8, 2011