Microsoft’s mobile platform is picking up steam this week, as two more vendors to get behind the Windows Mobile 6.5-based devices showed off their wares.

Taiwanese manufacturer HTC unveiled the HTC HD2, its first Windows phone to sport HTC’s in house designed Sense interface. Speaking at the recent launch of the Sense UI, HTC CEO Peter Chou said: “Our strategy with HTC Sense is to allow us to differentiate ourselves, and also to build a closer relationship with people.”

Chou revealed that HTC has spent the last three years covertly developing a ’specialist software team’ to sit alongside its hardware unit. This has brought hundreds of software engineers to the company, which specialises in Windows Mobile and now Android handsets, he said.

“Today we probably have the most Android and Windows Mobile developers outside of Google and Microsoft,” Chou said. “HTC has spent millions of man-hours developing a better HTC-branded software experience that makes all of this simple and engaging to customers.”

The HD2 will be available later this month with selected operators across Europe, before rolling out to other regions in the coming months.

Moreover, newly purchased HTC Touch Diamond2s and Touch Pro2s will now include Windows Mobile 6.5 software, while upgrades will be offered to existing customers that previously purchased the Touch Diamond2 or Touch Pro2 phones.

In related news, Chinese handset and equipment firm ZTE also announced two Windows Mobile 6.5 devices to be launched on TMN’s network in Portugal.

The SilverBelt and BlueBelt II handsets have been customised by ZTE specifically for the Portuguese market. The BlueBelt II handset is an ultra-slim candy bar style UMTS smartphone with a five megapixel camera, touchscreen and modified QWERTY keyboard. The SilverBelt is a similar form factor device with an added accelerometer.