it is 1080p, just look at the youtube trailer, you have the option for 1080p, which is not the case for other trailers.

the option1080p  in youtube is for MK8 too?

Saw the tweet, guessing up scaled 1080p because 1. A rep made the statement. 2. The jaggies are fairly obvious in every released video and 3. Even without AA jaggies aren't noticeable in 1080p (See point 2)

It's a 2d platformer on a system more powerful than PS3. They better be able to get it to 1080p!

I'm guessing upscaled as well.  Guess we'll see.  It still looks great.

Mario Kart 8 trailer is 720P, so it kinda proves it.

Mario Kart? Smash Bros? Bayonetta?

Anyway does it even matter if it's 1080p? It looks great regardless and its 60fps which I think is more important.

no i heave prove it 15min before and its 1080p

i think this is 1080P simply because is reusing some Wii assets
same as Smash.
i like this aproach of Wii type grphics but with shader 4.x and 1080p/60fps and greater texture detail too of course
of course i dont mind going full detail and 720p/30fps for X for exsmple...or Zelda U

It is clearly a 720p game. Just look at those 720p native screenshots, the aliased edges show native 720p.

The assets in those pics are barely 720p. Except for the main characters or enemies, textures are targeted for a lower resolution. Geometry of the scenery is angular, meaning low polygons count. I would not see the point of a 1080p image if you have 600p textures and low geometry in it.

They carefully chose their assets in order that the game would run at a perfectly locked 60fps with responsive controls. Which is perfect for a Donkey kong game.