On Tuesday, Microsoft and its device and wireless-carrier partners will unleash a new generation of smart phones that utilize the new Windows Mobile 6.5 system. Designed primarily as a stop-gap between the out-of-date Windows Mobile software that currently dogs today's devices and the Windows Mobile 7 version that Microsoft promises for the future, Windows Mobile 6.5 does offer some interesting new functionality, including touch-screen support, an online apps store, a better mobile browser, and more of a consumer focus.

If that sounds an awful lot like the iPhone, well, that's by design. Apple's successful device caught Microsoft flat-footed when it debuted two years ago, and Windows Mobile 6.5 is its first (belated) response. According to market researchers, Microsoft's share of the smart phone market has eroded since Apple released the iPhone; in the most recent quarter, Windows Mobile controlled just 9.3 percent of the market overall, compared with 12 percent a year earlier.

Aside from the iPhone-like functionality, the biggest change in Windows Mobile 6.5 may be that Microsoft has pushed its partners to ship products based on the new system a bit faster than in the past. The effort seems to have paid off, and Microsoft points to a host of device and wireless carrier partners that will deliver new Windows Mobile 6.5-based smart phones to customers in all major markets around the globe. In the United States, AT&T, Bell Mobility, Sprint, TELUS, and Verizon Wireless will all begin marketing new devices on Tuesday. These devices are being made by companies such as HP, HTC, LG Electronics, Samsung, and Toshiba, among others.

AT&T, for example, has already announced two Windows Mobile 6.5-based smart phones: the HTC Tilt 2 and the HTC PURE. Both come in iPhone-like enclosures, with touch screens, 3G support, and an HTC-enhanced UI; the Tilt 2 features a full-length slide-out hardware keyboard, as well. The PURE is available immediately.

Could Windows Mobile make a comeback? One recent report from analysts at iSuppli suggests it's possible. "Windows Mobile is facing a host of challenges, including rising competition from free alternatives like Symbian and Android, the loss of some key licensees, and some shortcomings in its user interface," iSuppli analyst Tina Teng wrote in a statement. "However, Windows Mobile holds some major cards that will allow it to remain a competitive player in the market. While Windows Mobile is losing some share to competitors in 2009, most of the alternatives cannot match Microsoft's complete suite of offerings."