Unfortunately, Nindendo's 3DS Software Showcase has passed without mention of AC:3DS --at all. It's still possible it will be mentioned on the floor, but it seems it wasn't at a state it could be shown, and no firm dates have been determined at this point. I would be very surprised if any news of substance were announced following an event intended for announcing upcoming 3DS releases.
Considering other titles were mentioned that won't be released until later this year during the holiday season, it may stand to reason that AC:3DS won't be available this year. Of course this is speculation at this point. But that's all we're left with for now. At this point, more was mentioned at last year's E3 regarding AC:3DS than this year's event.
Total bummer. Sorry guys.
Stay tuned of further news we may have.
Animal Crossing: The other oxygen.