When the new technology of writing started taking off the ancient Greek philosopher Soctrates was dead against it. He thought that it would damage learning as it would affect people's ability to remember stories passed on by oral tradition, and most importantly he believed that learning was best received from a teacher, or discovered through discourse. Learning on your own from a book was a very poor substitute in his eyes.
And in some ways he was right. The spread of written language has ultimately lead to the disappearance of the oral traditions of passing on stories. I have no doubt that it has affected our memories, Ancient Greeks could no doubt remember long stories / dialogues much better than us.
However he completely failed to appreciate the amazing amd transformative benefits of the written word: an educated society, the ability to share information and the advancement of knowledge etc etc, as well as the simple pleasure of reading a book :)
I expect Socrates would have been horrified to see a child wrapped up in a book, the same way some posters here seem to think that children on computers are being deprived of something.
I'm not denying computers can be overused or badly used, but suggesting that by focusing on the negatives, people are missing the point entirely! We are at the beginning of an incredible leap forward in technology, and in the technology available to us as individuals.
The power of the internet is incredible for example. It is up to us to teach our children to use it well, and if they can start this early, well why not? If your child sits on it playing non educational games all day then that points to a lack of imagination from the adults rather than a problem with the technology IMO. (do you select good books for your kids to read?)
It will cease to be such an issue as the technology becomes cheaper anyway. Affordable tablets will become far more available in years to come.