Definitely looks in game. Whether they've been touched up a bit remains to be seen, but it definitely looks in game to me.
Can pretty much guarantee the Mercenaries pics are genuine because otherwise they're pretty poorly doctored, they LOOK like a game. Revelations looks much better, but then it doesn't need to draw a dozen enemies on screen at once so it can afford to look better.
Oh and, especially with Mercs, it really goes to show how quality texturing can really hide a lower polygon count. Also I imagine there's normal maps, or bump maps or whatever to give more dynamic to the landscape.
Both are touched up in the resolutions and general sharpness department, but all the assets seem genuine. We've seen footage of the games and they look quite similar, just at a lower resolution and with more jaggies.
MT Framework on the 3DS is pretty spiffy. Capcom have got so many modern shaders running. Really does wonders in making their games look great.