The 64bit client is still in beta but details on how to run this will be released soon. I am really looking forward to the 64bit client as it should enable faster load times once inital content is cached as well as more UI mods with less worry on hitting the 2gb memory cap of a 32bit program.
The other huge bonus is the new Battletag / RealID raid system where you can raid with anyone in the game no matter what realm they are on.
Full patch notes below:
