I joined Nikonians because I am going through what you and others are going through with my D7000. I bought it in August of 2011 assuming it would replace my D300 as main body. Love my D300, it is a bulldog of a camera and the memories with it are priceless. So with excitement I started shooting usual subjects with my D7000. Nature, birds, snakes turtles and freelance news paper gigs. Right away, I was producing out of focus subjects. Well, as a seasoned, passionate photographer, I was not happy with the results I was getting. I put the camera down and went back to my trustworthy D300. As a result my warranty has run out. I just thought it was me and I was not used to it yet. I took the easy way out and did not deal with the problem at the time.
Making a longer story short, I picked it up again, LEARNED the modes of a bit more advanced auto focus system and when it gets recalibrated, I can't wait to mess around with assuming it is not back focusing anymore.
I feel for anyone getting a D7000 with these issues and if you are having those problems, you are not alone.