Most screenshots showcased for Metal Gear Solid V: Ground Zeroes have been released in 1080p resolution, but not all of them. At least two of the screenshots were quite evidently in 720p, not only due to the pixel count of the screenshots themselves, but also because of the very visible aliasing.

Below you can see two screenshots released in 1080p, with barely visible aliasing and soft shadows. You can click on each picture to see the full size version.

Note: the shot at the top of the post is just an artistic rendition to showcase the concept, and it's not representative of the actual looks of the game.

And just below there's the pair in 720p. The platform showcased has not been confirmed, but the shadow are rougher and textures show a lower resolution, matching what said by Director Hideo Kojima himself about the PS3 and Xbox 360 version.

While the screenshots still look good, aliasing is very evident, especially if you observe the barbed wire on the wall and the spotlights.

The resolution of the game on PS3 and Xbox 360 hasn't been confirmed yet. All we know for sure is that they'll run the game at 30 frames per second as opposed to the 60 of the next generation version. Will they also have a 720p resolution as opposed to the 1080p of the next generation consoles? We can't confirm it for now, but the 720p screenshots seem to match everything Kojima-san said about the version on current generation consoles.

Of course we'll have to wait for an official announcement or a pixel count of the released game to be sure, but it'd take a development miracle for machines that are now seven and nine years old to run this game at a 1080p native resolution, even if only at 30 frames per second.

[Thanks DieH@rd from NeoGaf for Fishing up the 720p screenshots]