HTC and Samsung are at the head of the line of U.S. handset vendors offering Windows Mobile 6.5 phones, the first smartphones based on Microsoft’s new OS that are meant to finally give Microsoft-powered phones features that are on par with those available in Apple’s iPhone.

At an event in New York Tuesday Microsoft also launched its Windows Marketplace for Mobile with 246 applications now available in the mobile apps online store, a small number in comparison to the tens of thousands of applications available on Apple’s App Store for the iPhone.

Windows Mobile 6.5 is the first OS to allow people to download apps for the devices, and Microsoft said that more than 753 software developers worldwide are continuing to build out the catalog.

Microsoft showcased the new phones at an “open house” event in New York that also highlighted other products Microsoft will have on sale for the Christmas holiday shopping season, the ZuneHD and XBox 360 among them. The company also quietly rebranded its new mobile devices “Windows phones,” appearing to distance them from the “Windows Mobile” moniker.

Microsoft Entertainment and Devices Division President Robbie Bach said Microsoft’s aim with all of its new entertainment and mobile devices is to provide innovation to change the way people live their lives. “The technology we are working on today is about changing lifestyles and changing industries,” he said at the event.

Bach said that while in the past, Microsoft’s Windows phones were more suitable for business users, with features geared toward that demographic, the new Windows phones are more consumer-oriented. “We’re adding to that integration with your lifestyle,” he said.

While Microsoft has been touting Windows Mobile 6.5 as an innovative technology that also will help the company compete better with Apple in the smartphone market, analysts have reacted coolly. Some have suggested Microsoft altogether abandon the OS, which has been losing market share and is more than two years behind Apple in terms of features.

For example, the new Windows phones My Phone feature — which allows Windows Mobile users to synchronize information between their phone and the Web — is akin to the MobileMe service from Apple launched last year for iPhone.

In North America, customers can now purchase Windows Mobile 6.5 on the HTC Pure from AT&T and the HTC Imagio from Verizon Wireless. The Samsung Intrepid from Sprint will be available on Oct. 11, and the HTC Tilt 2 from AT&T will be available in the coming weeks.

In Europe, HTC and Samsung also will offer phones, alongside handset providers MDA, Toshiba, LG and TMN.

Bach said that Microsoft plans to ship 30 Windows phones in 20 countries by the end of the year, featuring a range of form factors that will provide choice to customers.