Optimus 2X ( LG's tegra2 phone ) newly updated firmware can play 720p high profile.
there are some firmware changes from nvidia or LG.
we have GalaxyTab 10.1 test device. it can play 720p high profile h.264 movie.
(i'm one of diceplayer dev team. we are developing diceplayer for honeycomb )

i think moto can do this to xoom. ( but i don't know when moto release new firmware . )