As a matter of fact, what I find really odd about this (admittedly cool looking) "poster" is that it's actually been around for quite a while. As a matter of fact it's been floating around online for at least six months. Quite a few websites/blogs are highlighting this as a real and new poster for the film, but it's simply not true. As a matter of fact you can see here at this snapshot of AdvancedIron.org from December 30th, 2006 that it was used on the homepage of that site.
I suppose the issue is that some blog author who is not a rabid Iron Man fan stumbled across this thing, had never seen it, assumed it was new and threw it up on his site. The web being what it is, there was then a domino effect with other movie sites reporting this was the official poster, once again without any sort of legwork to determine whether or not that was true.
So yes, it's a cool image, but no, it's not an official poster. :-)