Obchod S Mobily doesn't offer a launch date, but it does give us a price. The price listed is 14,995CZK which translates into a rather pricy $766.66USD. But remember, this is a high-end model. On the other hand, the price could be a placeholder and without confirmation from Nokia, we will have to wait and see how deep into your wallet you will have to dig for this model. It should also be pointed out that some of the specs on the listing are incorrect and since the Nokia Lumia 800 shows up elsewhere on the same site, the discrepancy can't be shrugged off as a case of Lumia misidentification.
One last note, There has been speculation that other variants of the Nokia Lumia 900 other than the one that AT&T is rumored to have a 45 day exclusive on, would be well endowed with a 12MP camera. The listing on the Czech site shows an 8MP shooter. Of course, that doesn't mean that another version of the Nokia Lumia 900 won't be produced with a 12MP camera.
source: ObchbodSMobily (translated) via WPCentral