(FORTUNE Magazine) – Your next computer probably won't be a computer. It'll be a phone, an organizer, or a pager. You'll use it for communications: to read e-mail on the go, to find the nearest gas station, to check your bank balance, to buy groceries. And it will connect to the Internet wirelessly.

At last, mobile data communications products are about to become mainstream. Over the next few years, as more of us spend more time online, portable digital devices will supplant stationary desktop systems as our preferred routes to the Internet, outside business and entertainment, which require too much bandwidth. Our most personal computers won't be PCs. I know this as a trend spotter, professional optimist, and buyer of countless electronic gadgets (now abandoned)--and because so many companies large and small are trying to make it happen.

As technology advances let wireless devices receive data at higher and higher speeds, major online services like America Online, Microsoft's MSN, and Yahoo are adapting their offerings for mobile use. Prominent cellular telephone carriers, including AirTouch, AT&T, GTE, and Sprint, are providing wireless Internet connectivity. Nokia plans to make its cell phones more intelligent by incorporating the operating system developed for the Palm organizers. Sony will soon make Palm-based gadgets too. Telecom equipment maker Ericsson is launching an effort to develop mobile e-commerce. A pager-on-steroids known as BlackBerry, from Research in Motion, has become the new must-have gizmo among my venture capitalist friends, who tend to be e-mail addicts.

What's emerging is a third-generation Net based on pocket-sized, untethered devices. The earliest Net linked minicomputers and dumb terminals; then self-contained workstations and PCs got to plug in and use an exploding array of data and applications. And now, through intelligent gizmos generally known as personal digital assistants--a catchall that includes digital cell phones, organizers, laptop computers with wireless modems, computers in cars, and who knows what kind of doodads-to-come--the Net is floating free of its traditional anchors. This wireless Web, as many are calling it, will give rise to many new companies, which are the vein I like to mine.

For example, several startups are supplying information to be sent over the air for display on the latest generation of Internet-enabled cell phones. AirFlash.com of Redwood City, Calif., can send information based on your location as determined by the cellular network, which should help if you're searching for the nearest gas station or ATM. A startup in Santa Clara, Calif., @Mobile.com, is working with Yahoo and others to beam weather forecasts, stock quotes, and even available tee times at the local golf course to mobile phones. A service called Unimobile from Gray Cell of Campbell, Calif., enables users of personal computers to send instant messages to wireless phones in any of 55 countries.

For those with wireless organizers, such as the Palm VII, AvantGo.com in San Mateo, Calif., offers a hundred information services, including material from Fox Sports, the New York Times, and Salon.com. A new company in Austin, Texas, Wayport, is rolling out a nationwide service that will provide travelers with fast connections to the Internet, both wired and wireless, in hotels, conference centers, and airports.

Several Canadian firms are active in the area. News, sports scores, and even horoscopes are available over the air from QuoteCall.com of Ottawa, Ontario. To help you determine which messages you want to read on the road and which to save for your return to the office, a service from AmikaNow! of Kanata, Ontario, will review your e-mail and transmit to a cell phone or organizer the key words and phrases from messages that appear important. Startup 724 Solutions of Toronto is working with Bank of America, Citibank, and others to enable wireless banking.

One of the most promising companies, I think, is iScribe of San Mateo. The outfit has developed server and networking technology to enable physicians to use Palm organizers and other handheld devices to automate the processing of a few key tasks, such as ordering prescriptions and lab tests, capturing charge information, and referring patients to specialists.

All this has implications for the architects of data communications networks, who now must design systems for a world in which network clients are connected intermittently and from varying locations. Security will have to improve to give intelligent portable devices a significant role in financial transactions--for example, downloading digital cash into a bank card over a cell phone. And the spread of mobile data communications will alter the way we interact with digital devices. Years ago, desktop computers were regarded as peripherals to a network of mainframes. These days, mainframes are seen as peripherals to our PCs. In the not too distant future most of us will regard every other computer on the Internet, including our own desktop computer, as a peripheral to our personal digital assistant.

Indeed, my principal concern is not with the spread of mobile data communications but with some of its social consequences. As omnipresent wireless data blurs the distinction between work and the rest of life, will too many people end up working everywhere, all the time?

Now, I'm fond of gizmos (although no more than most other people you might see hanging out at Sharper Image). More important, however, I find freedom in being tethered. It's liberating to know that I can be reached anywhere at any hour, and that I can make a call, send an e-mail, a page, or a fax, or even grab some data from the Internet, wherever and whenever I get the urge, be it on a plane, from the back of a taxi, from a mountaintop. But the wireless devices I carry--a SkyTel pager, a digital StarTAC phone, and a Palm VII--all come with switches. They can be turned off. I carry them because they put me in control.

RICHARD A. SHAFFER is founder of Technologic Partners, an information company focused on emerging technology. Except as noted, Shaffer has no financial interest in the companies mentioned. For an expanded version of Watch This Space, visit www.tpsite.com/tp/fortune/. If you have comments, please send them to shaffer@technologicp.com.