A few embryos and some stem cells have been created, but that's about it.
Cloning an entire human being is pretty worthless and that's where most of the religious nuts go crazy, but in reality nobody wants to do that. But what is useful would be creating lab-grown tissues and organs - cloning could allow us to create lab-grown bone marrow that would perfectly match a patient for a transplant, or a lab-grown kidney or liver tissue or whatever it might be. If it is cloned, it contains all of the cellular markers of the original host and would eliminate rejection and graft v host disease in transplants. And cloning stem cells paves the way for not only all of this but for anything that stem-cell therapy and stem cells in general are used for, including research.
Why hasn't a human been cloned yet? Well besides uselessness of cloning a human just for sh#ts and giggles (and the fact that funding/support for this would be nonexistent), there are a bunch of challenges that we don't face when cloning animals. First and foremost is a supply of egg cells - with sheep or cattle or whatever, we can just harvest a sh#t ton of ovaries and get egg cells. Thousands and thousands of them without too much trouble. With humans, you're talking hormone therapy and a surgical procedure by a willing donor in order to get just a few egg cells. So that's the big thing. And the unique developmental biology of each organism in its embryonic stages and the implantation procedure (also needing a willing host mother rather than just a female lab animal) poses a challenge because it means you can't just do the sheep procedure with a human egg - it wouldn't work. But I'm pretty sure we've gotten to the point where we've at least created some viable embryos, so it's a start
Unfortunately, the religion nuts start foaming at the mouth when they hear the word "clone" so they're sabotaging research that will produce literal medical miracles in the future. So it goes.
