QUOTE(raylee914 @ Nov 22 2011, 10:22 AM)
then is that we need to change our Battle.net info to US address in order to be able to trade in RMAH with the westerner or just buy the us set? I am really confused...
or is there any article or announcement that explain the AH region restriction?
If I am not mistaken battle.net info will sync their servers every day.
I had previously link my WoW TW to my battle.net acc. I did it through the SEA portal. I had problems login on to WoW that day. So I did some investigation. I found out that if I login to battle.net through the TW portal, my WoW is still not link to it. But it had info about my SC2 and WoW:US. Then I change the region back to SEA, I can see all my other games plus WoW:TW. Change the region to US and the same thing as the TW one.
After a day later I check back at the TW portal and indeed my WoW:TW is there, same as US. And I can play WoW:TW again

So do take not of this. When changing acc info.
Oh regarding your question, yes changing your address to a US address will make you able to trade with "Ang Mohs" provided you can prove you really live there.
See the vid below for more details
http://youtu.be/ZirE9nd8ILc