Today was my older son's first day of preschool. It's the same school he attended last year, and he was eager to get going, happy to see his friends and teachers. It's amazing to me to think of how much he's grown in the past year, and what he'll be like a year from now.
One of the things that never gets talked about in the endless discussions of whether child care is good or bad for children -- which are typically framed as being about whether or not women should work outside the home-- is that non-employed parents use child care as well. We send our son to preschool because he likes it, because it's a good opportunity for him to learn social skills (sharing, taking turns), because it gives our other son a chance to have some one-on-one attention, and because it gives my husband a break.
Child care is expensive, of course, so it's mostly affluent non-employed parents who use it -- full- or part-time nannies if their children are infants, preschool if their children are older. Very low-income parents may also be able to send their children to Head Start, which was explicitly designed to try to make up the gap in the learning opportunities available to poor children before they start school.