How young?

Question
A child should be how old before you would let him have a pet rabbit?

Answer
There's a lot of debate about that.  

You know your family patterns and child better than anyone. But the child needs to be old enough to properly pet and handle a rabbit.

If you have a young child who is calm, gentle and attentive  to animals it may work.  You also need to feel comfortable that you can leave the child and the rabbit unsupervised without the rabbit getting hurt or the child scratched or bit.  

Rabbits are quite different from many other pets.  Loud noises, being held, or roughly petted can be stressful for them.  Your child will need to be able to gently interact with the rabbit.

One other thing to consider is who will be taking care of the rabbit.  Rabbits are high maintenance pets.  Your child will have to be responsible enough to care for it, or you have to be willing to take care of it.

Another consideration is that rabbits can live 5 to 10 years.  Children get busy with activities as they grow up, and you'll want to take that into consideration, so the rabbit doesn't end up lonely and unattended to.

One other thing to think about is the breed of rabbit.  Many pets stores sell dwarf rabbits, and there is a myth that dwarf rabbits are more friendly than other breeds.  Each rabbit is an individual and ideally you want to spend some time with the rabbit before bringing it home.

The last thing to consider is the age of rabbit to bring home.  A very good choice is an adult rabbit that has already been fixed.  The rabbit will be calmer, "possibly" a little less destructive, and you will completely miss the territorial behavior of a rabbit that hits puberty.

If this is your first rabbit some good web resources are:
http://www.rabbit.org/index.html
http://homepage.mac.com/mattocks/morfz/rabrefs.html
http://www.paperglyphs.com/rabbits/rabbittalk.html
http://www.bio.miami.edu/hare/hrs.html

And this site gives some info on tips about rabbits living with children:
http://www.rabbit.org/faq/sections/children.html

I hope this information helps