Well Pinterest now lets you know if you already pinned something! Revolutionary in my world- after reviewing a few boards and I had the same thing like 7 times. I always think to myself "I guess I really liked it..."
It even nicely phrases it..."Pssst..it looks like you've pinned this before." So helpful I'm sure this will be even more useful when my Pinterest use spikes over the summer. Hope you can use this helpful feature! The notifications are also very handy now with the update as well :)