They're everywhere. Wireless data devices are our constant companions: They ride with us on commuter trains, go to work in the office, and amble about with us on country roads, city streets, and back alleyways. But the vast majority, particularly cell phones, are used exclusively for talking—not for delivering data.

That's a shame, because wireless devices hold the potential to work much harder for us, especially as we make the shift from a voice-centric world to one awash in mobile data. Change is slow, however, particularly in the U.S., where getting data the wireless way is expensive, complicated, and unreliable, partially because of the various incompatible networks and services. Some of the blame could even be placed on handsets, which we discuss later.

In 2001, only 3 percent of the 111 million mobile-phone subscribers in America used a mobile-data service, says Charles Golvin, senior analyst at Forrester Research. But by 2006, he predicts that two-thirds of the 180 million mobile-phone users will rely on data services. Most research suggests that greater acceptance of wireless data will occur as the phone networks roll out new data-based services, including access to online entertainment and m-commerce.

The transformation from using phones for basic communication to using them as all-purpose data devices that enrich our personal lives through constant communication is already evident in the use of Short Message Service (SMS), which lets cell phones send brief messages to one another via their keypads.