I dreamed that I was holding a real, beating heart in my hands and I was supposed to put it back, but after waking I couldn't remember who I was supposed to put it back into.  What could this mean?

That's your dreaming heart. You're supposed to take care of it.

How do I take care of my dreaming heart?

Well, I sure wouldn't know... :) Not having had the experience you did in your dream, I can only assume that it belonged back inside your dream body. Maybe you just wanted to see it, who knows? It's a mystery.

The heart doesn't only stand for giving and accepting love but also for health, activity and joy of life.
Does that help? Actually I'm hoping it doesn't. You're not depressed or stressed out, are you?

(The impression I got when I was reading your first post was that you're looking at it but not using it.)

take care,
Vagabound

Thanks, some helpful ideas.  Yes, my memory of my dream was that I was responsible for the heart and responsible for putting it back in....someone, but I don't know who.  Maybe me, but I simply can't remember, though I'm sure I knew exactly what I was supposed to do while I was in the dream.  It just slipped away from me when I woke up. 

Quote:

though I'm sure I knew exactly what I was supposed to do while I was in the dream

In that case, don't worry about it, because you know what to do, even if you don't remember. Your subconscience will make you do the right thing. If it keeps bugging you, just ask them to tell you again.
(My guess -if it's your own heart- would have been; you have the right ideas, know what to do, now it's time to go out and have fun with it.)

take care,
Vagabound

maybe  someone you know from before is waiting for you to find them, possible someone who loves/loved you?

Someone who loves me was embracing me in a dream last night, but sadly I do not know who it was.  Sadly I do not know how to find him in this existence.