Our sibling site, TreoCentral.com, reminds us about the NY Times report that even hands-free cell phone (including iPhone) use while driving radically increases the risk of accidents:
Studies say that drivers using phones are four times as likely to cause a crash as other drivers, and the likelihood that they will crash is equal to that of someone with a .08 percent blood alcohol level, the point at which drivers are generally considered intoxicated. Research also shows that hands-free devices do not eliminate the risks, and may worsen them by suggesting that the behavior is safe.