Here's (to my knowledge) the latest info that's been posted regarding the planned trade changes:
"
The new trading changes aren't in the March 1.1.0 patch - there are two reasons:
a) We're keen to deploy them as soon as they're ready. There's no real need to wait for the next four-monthly patch.
b) The new trading stuff is not ready yet. It's a major system overhaul and we're still working on it. I'm really sorry about the delay.
As for how it works, the current plan is a combination of public stash tabs (to make it easier to find items) and separately, an asynchronous cross-instance-website trading system. You can basically trade (without buyouts) across the game and website. The trades and offers are still there when you log in later, so it's possible to trade with offline people or people who aren't in your game area or are on their phone or work PC.
