RDP,
There is content on the iPads that is very child appropriate.  As you said, the key is parental supervision.  
My point is that parental supervision has always been important and continues to be.  Also, parental supervision has often been lacking in the past, just as it is now.   
To be frank, I am impressed with any 9yr-old who is able to re-rout an internet router.  That kid has much potential which should be channeled toward productive and fun ends.
Yes, parents ought to be familiar with the technology that their children use.  I think that parental monitoring and involvement has changed, but so has the world.  Changes are always worrisome to those who grew up earlier.  I think that today's parents are well-equipped to handle this, if they make the effort.