We’ve gotten some more information on the upcoming Nokia Ace for AT&T — whose codename for the device is Eloko — including confirmation that it is indeed the Lumia 900 which will be sold globally as Nokia’s flagship Windows Phone. Although we thought that there was a chance Ace would ship with the Tango build of WP7, it’s now been made clear that Mango will be the flavor of choice at launch. The main specs here should sound quite familiar to Microsoft observers: ~4.3-inch WVGA display, 512MB of RAM, eight-megapixel camera, and a capacious 1830mAh battery.

Although it will almost certainly be sold carrier locked, Ace — like most modern Nokia handsets — will contain the 1700MHz band necessary for T-Mobile 3G, so we imagine that a workaround to unlock that functionality will arrive with the quickness. At 160 grams, Ace weighs 18 more grams than the Lumia 800, likely due to the combination of a bigger screen and LTE radio. Based on the phone’s reported dimensions, we were able to mockup a comparison shot with the Lumia 800 using those leaked 900 images from last week. Although it’s not apparent from the picture, both handsets have nearly an identical thickness of about 12 millimeters.

We’re expecting to fill in the final details in a few short days at CES, where Nokia has also been rumored to introduce another mid-range Windows Phone, the Lumia 719.

Update: BGR had this one scooped so long ago that we actually forgot about it. Key spec addition: 1.4GHz Qualcomm CPU. And naturally, the screen uses Nokia’s ClearBlack technology.