Tim Harford (aka the Undercover Economist) argues that the ubiquity of email, video-conferencing and other telecommunication media has increased the demand for travel (to conferences and meetings) and for living in big cities with networking opportunities. In essence:
... e-mail, internet networking and cheap phone calls have made it easy to maintain a lot of relationships. In principle some of them could be restricted to cyberspace, but how much fun is that? The same e-mail that allows you to maintain a long-distance business relationship also creates demand for more travel as people try to establish those relationships in the first place.
Although I think he raises a good point, surely at some point telco devices and face-to-face contact become substitutes. If more terrorist attacks cause large airfare hikes then surely people will rely more opn e-communication.
Also, having worked (rather unsuccesfully) in a telecommuting environment I can see the that face-to-face contact is very important in building relationships.
Perhaps then the effect that Tim is capturing is that Blackberry owners are more inclined to travel (and perhaps move house) for work purposes since they can more readily maintain their existing family/freind relationships through the use of email, cheap international calls, etc.