According to Paul Thurrott of Supersite for windows, Nokia is working on releasing what i would like to call "Lumia 900 extreme edition", it's said to pack a 12MP camera and should be available on other mobile operators (Verizon, T Mobile, Sprint..) after At&t exclusivity deal with the Lumia 900 expires in 45days from March 18th.
he says his source is from a rival wireless competitor and he did advice we take this with a "grain of salt"OK wow, that's a lot to take in, so let's break this down, regarding the 45 days for Lumia 900's At&t exclusivity, if this rumour is true, that would really suck for At&t, Microsoft, Nokia or whichever one of them is investing that rumoured $200million on ads. I'm no marketing guru, but It doesn't take one to know that investing that much money in ads and then have Verizon and other networks come out with an improved version of the Lumia 900.
The rumour that At&t is giving the Lumia 900 a Hero status doesn't help either, 45 days is just to short to make a phone exclusive and At&t should know this (given that the iPhone was exclusive to their network for 4yrs+)
I do reckon this 12MP phone in question will most likely be an N8 variant running Windows Phone, but we'll see!
Like Paul said take these with a grain of salt.