A report from Kotaku notes that Nintendo's Eiji Aonuma just sent out a new Swapnote earlier today teasing "new Legend of Zelda games." Aonuma is the producer on the popular franchise and while Nintendo themselves have not officially confirmed if one is in the making, Aonuma has expressed interest in making one for the 3DS.
"Hello, this is Aonuma, Nintendo's Legend of Zelda producer," he scribbled in the note. "Did you enjoy The Legend of Zelda: Ocarina of Time 3D? Thanks to everyone, The Legend of Zelda series had a very happy 25th anniversary. I hope you're looking forward to new Legend of Zelda games."
If you don't already have Swapnote on your 3DS, you can download it for free from the Nintendo eShop. You'll have to activate Spotpass as well in order to receive notes from Nintendo.
We haven't received the particular note at this time of writing, so it's all on Kotaku. A new Legend of Zelda title for the 3DS would indeed be pretty exciting news.