The battle for the corporate palmtop heated up earlier this year when Microsoft introduced Windows Mobile 6, the latest evolution of its johnny-come-lately mobile platform which is now challenging perennial market leaders BlackBerry and Symbian. Is WinMobile 6 a killer shot?

As we saw in the last installment in this series on advanced mobile applications, some analysts believe WinMobile is the platform of destiny. "I think at this point the game is over. Microsoft has won," Ken Dulaney told us. Dulaney is vice president of mobile computing at Gartner.

However, others say that unlike in the battle for the corporate desktop—which pitted PC against Mac 20 years ago, and ended in almost total PC victory—the mobile device market will likely support multiple platforms for years to come. "I think the market is big enough to accommodate three, maybe four leaders," says Nathan Dyer, an analyst in Yankee Group's enterprise mobility group.

Certainly Research in Motion, maker of the popular BlackBerry platform, is conceding nothing, and doesn't appear to be suffering in the marketplace either. It recently reported a 16 percent rise in quarterly revenues year over year and announced that its base of customers had broken the 9 million mark.

One thing BlackBerry brings to the battle is intense customer loyalty, analysts says. "The customers we have today tell us that if the functionality is not there, they're not going to use a platform [Windows] just because it happens to be their desktop platform of choice," says Jeff McDowell, the company's vice president of global alliances.

Maybe, but despite its recent successes after a down couple of years fighting legal battles, one senses that RIM may be a little on the defensive these days. Microsoft is coming hard and, notwithstanding what McDowell says, it has a good story to tell about why enterprises should choose the Windows Mobile platform for developing and deploying applications.

For one thing, Windows Mobile has caught up with BlackBerry on the e-mail front, or so Microsoft claims. In the last installment of this series, we quoted RIM's McDowell saying that, unlike BlackBerry, Windows Mobile could not do "true" push e-mail - automatically and securely transmit e-mail to a mobile device as soon as it's received at the mail server. But that is no longer the case, says John Dietz, group product manager for Windows Mobile in Microsoft's mobile communications business.

"With Windows Mobile 5, they were correct," Dietz says. "We had a push-to-pull system. That was their huge advantage."

But even before the introduction of Windows Mobile 6, with the release of the Messaging Security and Feature Pack (MSFP) for WinMobile5 in February 2006, the platform could do true push e-mail, Dietz says. The first devices supporting MSFP began appearing last summer.

Windows Mobile 6 added more security features and easier integration. The first handhelds using WM6 are beginning to appear now.

McDowell also suggested that BlackBerry was a superior platform because, unlike Windows Mobile, it could push corporate data to a device to support CRM and other advanced mobile applications, much as it pushed e-mail. Also not true, Dietz says. "That is out-of-date [information]. There are a couple of ways [with WinMobile] to push out corporate data using the same mechanisms that push e-mail uses."

Whatever the relative technical merits of the two platforms, the Microsoft message is evidently getting some traction. If you look at the installed base of converged devices that include phone and PDA functions - smartphones, PDA phones - WinMobile lags competitors such as BlackBerry and Symbian. But Dietz says research firm IDC is forecasting that the installed base of WinMobile devices will grow faster than other platforms, at a compounded annual rate of 57 percent over the next five years.

Equipment makers are flocking to the WinMobile bandwagon. "Last year, we sold 11 million Windows Mobile licenses for converged devices," Dietz says. "That was double the year before, and we expect to sell another 20 million next year."

The number of licenses sold is not the same as the number of devices in users' hands, he concedes. But it's a clear indication that Windows Mobile is on a growth trajectory. Although he mistakenly suggests that the number of BlackBerry subscribers is only six million, Dietz is right when he notes, "In one year, we sold through as many as their entire installed base."