But Microsoft faces a formidable competitor in Symbian, which has partnerships with chipmakers such as Texas Instruments and Freescale, among others -- joint ventures that are similar to the Microsoft-Qualcomm one and that should also lead to smaller, more efficient phones.*

Still, Microsoft has made significant inroads, establishing partnerships with 47 device makers and 115 mobile operators, including Sprint/Nextel and Verizon in the United States. And Symbian's brand name is much less well-known in the United States than in Europe, Japan, and China, which might make it tricky to fend off Microsoft forever, says Brewster. "Just out of plain-old familiarity, if people have a choice, they're going to go with Windows," he says. "It's an obvious extension of their office."

Before consumers can test out competing smart-phone operating systems, though, cellular carriers and hardware and software providers will have to overcome two major technological hurdles, says Creighton's Young. First is the difficulty in using smart phones -- or any cell phone -- in different countries where cellular carriers transmit signals using differing protocols. "The fact that I can't transition from one country to another, from a consumer perspective, it makes no sense," he says.

The second issue is confusion over the media content available on cell phones. As demand for local news, comedy shows, and sports clips increases, for instance, media companies, device makers, operating-system providers, and mobile carriers will need to establish relationships that allow the public to select from a large amount of content, without confounding them with proprietary rules, Young says.

Many experts think Microsoft is positioning itself well for this race. "Frankly, I would guess that in years to come, Microsoft may well be pushing Symbian out fairly quickly," says Young. "The holy grail of mobile devices is to have a device in your hand that does everything that your desktop does at work," he says, and the Microsoft-Qualcomm deal "brings us much closer to that."

Correction: In the original version we stated that Symbian has partnerships with device makers as well as mobile carriers. Symbian has partnerships only with device makers.