I think Nokia is making a big mistake by limiting the Lumia 920 WP8 device to AT&T when they need to get this high end device on EVERY major US carrier. It comes as no surprise that the other carriers are revealing Lumia 8xx availability with T-Mobile getting an "exclusive" Lumia 810. I am not sure how it differs from the 820 the others are supposedly getting, but maybe it is the LTE limitation since T-Mobile doesn't yet support the LTE network. WPCentral put together a post that describes the differences between the Lumia 810 and 820 so check it out.
The Nokia Lumia 810 will support the fast T-Mobile HSPA+ network (trying to find out if it supports their 42 Mbps top speed). The device sports a 4.3 inch OLED display with Clear Black technology, 8 megapixel rear camera, 1.2 megapixel front facing camera, and all the great Nokia services such as Nokia Maps, Nokia Music, and more. There is no pricing are definite availability information yet.
This looks to be a nice WP8 smartphone, but given that Windows Phone has such a slow adoption rate I am still disappointed that only AT&T will get the high end 920 with all the Nokia innovation inside. Microsoft and Nokia need to get ALL new Windows Phone devices out on as many carriers as possible and stop messing around with stupid exclusives at this point in the smartphone battle.