If you combine the descriptions of kids' behavior, parenting styles, and the types of monitoring solutions -- you get many different permutations and possibilities for protecting kids on social networks.
If used properly, these devices not only protect, but can also help teach kids the right habits. And the goal should be to eventually remove the software or device once the kid has gotten older, or earned the required level of trust.
What's the best monitoring solution for your household? The answer depends on what type of child you have, what type of parenting style you've adopted and, mostly, how much risk you're willing to accept and embrace.