Everyone who has tried looking for Order & Chaos Online update notes has ran into this problem -- officially, there's barely any info and it's scattered amongst several sources.
I've decided to start tracking the updates in Game Updates and I'll post the info on this board as well. I should note that I play on iOS so when I post User Notes/Issues, they may not necessarily be occuring on Android.
Official Resources
Gameloft's Order & Chaos Online Facebook
Gameloft's Mobile Forum
Gameloft's Blog
Order & Chaos Online @ iTunes
Order & Chaos Online @ GooglePlay
Unofficial Resources
oac-head.com
oac-news.com
orderandchaosonline.com