It sounds like a dumb question, but how can you expect to create products and services for mobile users without a solid understanding of why they carry a mobile device in the first place?
Jan Chipchase, a researcher in Nokia's User Experience Group, has extensively studied the behavior of mobile phone users. Jan and fellow researcher Per Persson identified three behaviors that influence how people carry things: center of gravity, which describes where objects are most likely to collect in a house or apartment; point of reflection, the moment when you are about to leave a space; and range of distribution, which describes how far a person will let objects get from sight or touch. The research helps explain why people leave mobile phones behind or switch them off. It also demonstrates that mobile phones are playing an increasingly large role in people's live--both supporting and occasionally triggering personal crises. Read more in Jan's blog. - Eli