While such radio-controlled price manipulation may just be hypothetical, the technology isn't.
As wireless data networks spread the Internet, previously dumb machines are being connected and endowed with intelligence while portable communications devices are getting smarter.
Proponents haven't yet agreed on an adjective for the dawning new era in computing: Pervasive. Ubiquitous. Continuous. Persistent.
It's a piece down the road, this unwired world. Three to five years is the consensus among industry analysts. The telecom meltdown still acts as a ball-and-chain on new investment.
But there's no shortage of good ideas percolating - the soda machine scenario was one, posited by an IBM executive.
Industry insiders and invited journalists sampled some of the ideas at IDG's fourth DEMOmobile show in San Diego last week, getting a gander at prototypes and finished products.
Notable among them was the Vocera Communications System, which bundles the functionality of a walkie-talkie, phone and pager into a 1.6-ounce "badge" that users wear around their necks and operate hands-free with voice commands.
It's designed for hospitals, retail stores, assembly lines - anywhere mobile workers need steady contact.
Vocera's clever software uses voice recognition and transmits conversations in data packets using WiFi, the increasingly popular short-range wireless standard.
Vocera officials believe the product, hitting the market in October, will give harried nurses and internists a better way to keep in contact, especially during crises.
"What they have essentially today is overhead paging and running down the hall yelling," said Brent Lang, vice president of marketing at the 44-person Cupertino, Calif., startup.
Far less spectacular but pregnant with significance was Microsoft Corp.'s introduction of WiFi hardware.
Excellent alternatives from companies including Linksys and Netgear have been on the market for some two years. But Microsoft is apt to make inroads with software and a setup routine that look to be idiot-proof.
Sales of such WiFi equipment - which extends the Internet and other networks some 300 feet per hub - are on pace to grow 73 percent this year, according to the analyst firm Dataquest.
Compare that to the 10 percent growth that analyst Mark Lowenstein of the Mobile Ecosystem consultancy sees in the cellular market, and it's easy to understand the excitement around WiFi.
Lowenstein believes "an aligning of the constellations" that includes the mating of various types of communications standards is next in the wireless industry's evolution.
One company working to spur that vision is Idetic Inc. of Berkeley, Calif.
Idetic's technologies aim to provide seamless roaming between cellular, WiFi and other networks. A new product that Idetic announced lets you watch television on the latest cell phones.
With the maturing U.S. wireless market awash in some 100 million cell phones, startups have found clever ways to help corporations reduce telephony costs.
Among them is traq-wireless Inc. of Austin, Texas.
Its technology cut wireless phone costs up to 35 percent for General Motors, Continental Airlines and Bristol-Myers by matching workers' cellular usage with the cheapest plans, company officials say.
One traq-wireless service sends text messages to cell phone users detailing the name, number and e-mail address of a caller who left a voicemail message.
Another company hoping Americans will finally awaken to the utility of text-messaging with Short Message Service, or SMS, technology is PocketThis.
Already available in Britain, PocketThis lets cell phone owners send information they find on the Web - driving directions, train schedules and the like - to their handsets.
Such revenue-producing services are precisely what wireless operators crave given the huge debts they've amassed.
"The operators are absolutely desperate to drive a bargain," said chief executive Jerry Roest of Shazam Entertainment Inc. of London.
Shazam's market is people who get frustrated when they hear a song they like on the radio but don't catch its name or performer. To find out, they can call a four-digit number and record 15 seconds of the song, which Shazam's audio pattern recognition technology compares to a database of 1.5 million popular songs.
Callers get a text message with the requested data and Shazam splits the 75-cent fee with the wireless carrier.
All U.K. carriers offer Shazam, and Roest is looking for partners in the United States.
That may take time. U.S. wireless carriers are still developing the tools that will allow them to bill for such services.
And so far, many analysts say, the carriers have not been very good at reselling other people's products.
"It's not the technology that's the barrier," said Toby Maners, director of retail voice in IBM's Pervasive Computing Division. "It's getting the (wireless) companies to give up their contact with the customer."
By Frank Bajak