I beleive Blizzard implimented layering in 9.0, correct me if i am wrong.
The game as of right now is near unplayable in icecrown, the server lag is making spells and actions have significant delays. So…
I feel with the drastic server lag happening in the lead up for release i feel more work must be done to correct server lag as this will only multiply on release day… I hope the Blizzard team is working on addressing the issue come release day. as i feel if nothing is done, it will be a disasterous launch.