The New York Times reports about the confusion in the law over whether to find companies liable (to innocent victims) if employees using cellphones, two-way pagers, and other gadgets are involved in accidents.
I think almost every tort doctrine is implicated in this confusion, but the article particularly discusses (though it does not mention) respondeat superior (master-servant liability), which holds employers liable for the harms caused by their employees within the scope of their employment. The reason that's commonly given for requiring the harm to be within the scope of an employee's employment is that we only want to assign liability to the employer when we want the injury that was caused to be considered by the employer (and employee) as one of the costs of their business (like maintenance, rent, and other ordinary costs).
This is hardly the first time that tort law has been forced to deal with technological change: almost every torts casebook includes a huge number of cases where courts wrestle with the accidents caused by newfangled trains or automobiles. And, since this is common law, it's hard to predict how doctrine will develop to deal with cell phones, laptops, and other distractions of the modern road.
Also interesting is this paragraph in the article: "A study released yesterday by the Harvard Center for Risk Analysis concluded that a ban on the use of cellphones while driving may cost the economy just as much as the accidents caused by drivers using the phones." Tort law often balances the social utility of new technology with the harm that such technology poses to innocent victims. How the balance will come out, though, is anybody's guess (especially because courts can craft the legal rules--and thus the incentives upon actors--in so many ways).
Thanks to Lindsey Worth for pointing out the article.