I know there are a variety of philosophies on children and chores out there, I'm not really sure why, but there are. I actually met a mom who was looking for a babysitter who insisted her children not do any work until after they are 4 years old. Instead of expanding on my thoughts on this perspective, I'll just say, I did not take that job!
I believe that part of a parent's job is to raise people that will be responsible adults, capable of doing things for themselves and contributing to their families and the society. If we never require our children to do some work and learn what it means to keep a house then they'll always be dependent on other people to take care of them and their messes!
So as you can guess, my kids have chores! My daughter is not even 4 yet and she's had jobs to do for over a year. They are simple jobs and she is fully capable of doing them as she gets older her responsibilities will increase. For now she has to clear her plate after each meal, put her laundry in the hamper, put her clothes away (she just lays each stack on the shelf in her closet), clean up her toys and her room, and "make" her bed, she helps unload the dishwasher some times too. When we have cleaning days, she always chips in on tasks that she can do, like wiping off the table or putting things where they go.
I want my kids to understand that in a family, everyone has to help out. Everyone has to contribute to the functioning of a home. I have no desire to be a maid in my home and have grown and capable kids who don't do anything while I work around them.
Train UP your children!