Nokia just announced its Lumia 900 smartphone at CES. Long-rumored, the announcement finally took place on stage at CES, when the company’s CEO Stephen Elop introduced the 4G LTE-enabled device.

With 1.4GHz CPU, 512MB RAM, an 8-megapixel camera, the Lumia 900 presents many improvements compared to Nokia’s previous Windows Phone, the Lumia 800, starting with a bigger screen (4.3-inch AMOLED display).

nokia 900 520x520 Nokia finally announces the Lumia 900   and its coming to AT&T

While the Lumia 800 seems particularly well suited for emerging markets, on which Nokia has always been able to count so far, the Lumia 900 will also be available in the US, marking the company’s ‘re-entry’ into this tough but obviously highly attractive market.

Interestingly, Nokia opted for an exclusive deal with AT&T, which will be the only carrier to offer the phone in the US. Says Nokia America’s president Chris Weber:

“The Nokia Lumia 900 is designed specifically with the US in mind and the announcement of this collaboration with AT&T, in addition to other recent announcements, signifies a new dawn for Nokia in the US.”

Speed seems to have weighed on the partnership, as Nokia’s blog insists on data downloading capacities of “up to 50Mbps” through AT&T’s 4G LTE network.

While the Lumia 900 was “born for the USA,” the Finnish company will give Lumia a global push in 2012, taking its Windows Phones broadly around the regions where it does business today, Elop informed during Q&A’s.

As for the device itself, Nokia seems to have put a lot of effort into its camera – or better say, its cameras, since the Lumia 900 also boasts a front-facing one, not to mention a dual LED flash.

Beyond megapixels, its primary camera will include “exclusive Carl Zeiss optics, with large aperture (f2.2) and wide angle focal length (28mm)”. According to the manufacturer, these should guarantee high-quality images, “even in low-light conditions,” as well as hi-res video capture (720p/30fps).

Available in black and blue and also known as “the Ace”, the Lumia 900 is “the thinnest Windows Phone to date”, Nokia added. Another claim we’ll make sure to check has to do with the phone’s 1840mAH battery; according to Nokia, it could last for up to 7 hours of conversation, and a whopping 300 hours on standby mode.