We've been testing this for the past week internally, but be aware: there may be bugs.
I'll post again when a few orders have gone through without problems.
Update: There's no link from the payment area back to the store on purpose. It'll show up later, when this is officially announced. Also, the blank shipping info on the authorize.net email receipt is harmless.... we just don't tell them that. I suppose we'll end up telling them though, so people don't get worked up over it. Maybe there's a way to just kill that whole section on the receipt. I'll look into it.