Apple - Can iPad 3 play 2048×1536 video in its native resolution?
If you take a look at this page, it looks like the guy figured out how to get to 1920x1440 and even up to 2048x1536 using mpeg4 or h264.
The answer is no. The following lists the available format for displaying video output on the device:
Video formats supported:
H.264 video up to 1080p, 30 frames per second, High Profile level 4.1 with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats
MPEG-4 video up to 2.5 Mbps, 640 by 480 pixels, 30 frames per second, Simple Profile with AAC-LC audio up to 160 Kbps per channel, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats
Motion JPEG (M-JPEG) up to 35 Mbps, 1280 by 720 pixels, 30 frames per second, audio in ulaw, PCM stereo audio in .avi file format
So the maximum resolution is 1080p (1920 x 1080), there is no way to displayer higher, and certainly not native through the default media playing apps at least. 3rd party apps may well allow for this if they include a suitable codec, but I am not aware of any that do.