Not Android, but here is something that interesting - the iPhone 5 with the A6 chip looks like it can handle 720p hi10p videos quite well - iPhone 5: Flawless 10-bit MKV Playback - YouTube
That means the new iPad with the A6X should also give similar playback performance.
Um the The Nexus 7 with it's Tegra 3 processor is handling 1080p hi10p using MX Players HW+ mode with a few artifacts as linked previously.
As a note, just because you see little artifacts on a video does not mean the Tegra 3 can playback hi10p videos perfectly (some vids will show little artifacts while other will show a lot). Software decoding is the only way to go. Unfortunately, the Tegra 3 only gives usable playback on hi10p 720p video when it's OCed to at least 1.5ghz on all cores (tested on my Transformer Prime when I was able to OC up to 1.6ghz). While usable, you still see frame drops during high motion scenes or during panning. 1080p hi10p vids are out of the question.
Even the Snapdragon S4 1.5Ghz dual-core on a lot of new phones also has problems with 720p hi10p videos too - some videos will play okay, some will play fine, others will not play well using software decoding on MX Player. I personally never test hi10p vids using the hardware decoder because no SoC, to my knowledge, can hardware decode 10-bit videos.