Good news if you're looking for a white Nokia Lumia 900. It's back in stock over at ATT.com!
With the two year contractual discounts the white Lumia 900 will run you $99.99 and off-contract the Windows Phone will set you back $449.99. Additionally, it looks like retail stores are receiving inventory as well. In sampling three local AT&T Stores in my area, all three had the white Lumia 900 Windows Phones in stock.
On the down side though, the cyan model is still being listed as "Temporarily Out of Stock" online and local stores did not have any either.
Thanks, 5tephen, for the tip!