Windows 7 Phone Specifications: Microsoft’s rebirth as a mobile phone player in the US market.

Microsoft’s rebirth as a mobile phone player in the US market begins on Monday with the retail availability of five Windows Phone 7 devices, making for a global total of ten first-wave smartphones on the new platform.

Starting Monday we’ll see the first of three WP7 phones on AT&T and two more on T-Mobile. A single CDMA device has also been unveiled for Sprint, with announced availability in early 2011. Verizon, for what it’s worth, has publicly stated they don’t plan to carry any WP7 phones, though that may or may not pan out.

Early reviews of the HTC 7 Surround and Samsung Focus for AT&T and HTC HD7 for T-Mobile - along with the first WP7 phones launched in Europe - have already hit online and print outlets.

Dell’s Venue Pro is said to be coming to T-Mobile in time for Christmas and that Sprint phone, HTC’s 7 Pro, may go up for pre-order in early December with an early 2011 ship date, but we don’t yet have solid launch information on either device. There is some chatter that Microsoft employees will be receiving.

Beyond the initial wave of ten devices, we don’t know much about the future of Windows Phone 7 hardware - except that more devices are promised for early next year. So far the US market gets a slew of devices with fast 1GHz Qualcomm Snapdragon processors, 5 MP or greater cameras, and 3.5” or larger WVGA displays.

The LG Quantum and HTC 7 Pro will feature side-slider QWERTY keyboards, while Dell goes for the Palm Pre-style portrait slider approach with its Venue Pro. Venue Pro, along with Samsung’s Focus and the HTC HD7 will also feature 4” or larger screens, following the recent trend set by high-end, media-centric Android devices.

Microsoft’s own hardware requirements for WP7 smartphones lent some degree of sameness to this first round of devices, particularly with a mandatory 800 x 480 (WVGA) display resolution. Support for 320 x 480 (HVGA) displays has been promised in a future OS update, which will open the doors for lower-cost/entry-level devices. Aside from form factor, camera specs, advanced audio/video output and streaming capabilities, and internal storage capacity are a few of the more obvious ways for OEMs to differentiate their WP7 devices, hardware-wise.

So what about next year? Hard to say right now, though we could see devices from Asus, Sony Ericsson and Toshiba in addition to more phones from the names listed above. SE could be a wildcard here given the recent leaks surrounding their rumored PSP phone, which is said to run a version of Google’s Android OS. Kind of hard to imagine an Android/Playstation phone sitting next to a Windows/XBox Live phone in the same corporate lineup, no?

Most likely we’ll see at least one Blackberry-style candybar-plus-QWERTY device in early ’11, as this form factor has long been a favorite of enterprise users. And a PSP-style gaming phone would make sense on a conceptual level, anyway, given WP7’s obvious ties to the XBox platform. But “gaming phones” haven’t exactly been successful in the past — we’re looking at you, Nokia N-Gage — so don’t hold your breath on that one.

Here’s a spec sheet rundown of the first wave of Windows Phone 7 devices for the U.S. market: