(FORTUNE Magazine) – WITH THE STAGGERING SUCCESS OF its utilitarian black or blue, seemingly omnipresent BlackBerry devices, Research in Motion has become the hottest company out of Canada since ... since ... well, let's just say it's incredibly hot. This year RIM stock has shot up 160%, and by December it should pass the two million subscriber mark, meaning it has added a million new users since February--equal to the amount it acquired in the past five years. Part of RIM's success stems from the fact that the devices now work on standard wireless networks (during the dot-com days, they ran over a paging network). The rest is because no one has come out with a system for wirelessly sending and securing e-mail that works as well. In fact, the biggest downside to the devices appears to be addiction: The New York Times even warned this year about the danger of "drunk Berrying"--thumbing while intoxicated.

But in the tech world, where thriving markets are still scarce, others want in. The latest and strongest attack is coming from palmOne and its Treo 600, the cameraphone-cum-Palm appearing on executive belts coast to coast. In late October the company launched a new version, the 650, which boasts only a few innovations--a better screen, improved e-mail capabilities, Bluetooth, and a removable battery--but kept one of its strongest traits: a design that sets gadget-heads drooling.

"The guy who runs my operations group told me I could get his BlackBerry only when I pry it out of his cold dead hand," said Eric Martin, VP of technology at MW Manufacturers, a $240-million-in-sales supplier of windows and doors, which recently dumped its nearly 100 BlackBerries for Treos. Martin says he showed the BlackBerry addict a Treo 600, and he grabbed it right away: "It was a nonevent." Adds Jeff Hackett, executive director at another Treo adopter, Baltimore law firm Gordon Feinblatt: "When I put the Treo next to the BlackBerry, no one is going to take the BlackBerry."

Of course, looks won't be enough for PalmOne to threaten RIM, which controls about 90% of the $1 billion wireless PDA market, according to research firm Garter. PalmOne also needs to lure CIOs, who are more interested in the promise of productivity benefits. But reaching them is a new game for the consumer-oriented company. Currently only about a quarter of palmOne's sales come from big company purchases. To boost that, president Ed Colligan has deployed dedicated salespeople to help each wireless provider push Treos on their corporate clients. The incentive? As a Sprint vice president pointed out at the 650 launch, Treo users rack up higher bills with the carrier than do users of its traditional phones.

RIM co-CEO Mike Lazaridis dismisses the idea that RIM can be beaten in the market it practically created: With the BlackBerry, "you don't have to decide what software to put on it or how to configure it--there's none of that. It's not a do-it-yourself experience." What keeps him up at night, he says, is "not getting too distracted with overloading the things with features and complexity"--a clear shot at the do-everything Treo. But just in case, RIM recently launched a sleeker, phone-shaped BlackBerry, the 7100. RIM's making sure palmOne doesn't steal its users--even those hunkered over BlackBerries at the neighborhood bar. -- Daniel Roth