Why does it matter? Our eyes can't perceive 1080p at that size anyway. Higher rez means less battery life. HD movies will dither down to the proper size maintaining aspect ratio.
Our eyes don't work in resolution, but anyways there's little "ppi" increase to be gained by going to actual 1080p.
Standard resolution, that's already being used on million devices (these devices work on static resolutions unlike windows/OSX).
There is also some fidelity loss while "scaling" those few hundred pixels.