These laws will not help. Outlawing content will not make it suddenly disappear, it will just be a bit harder to find. Any attempt to filter content will be circumvented. Australia's attempt failed miserably back in 2007[1]. I agree that children are exposed to too much "crap" today, but using children as an excuse to censor material is a political move.
[1]: http://www.schneier.com/blog/archives/2007/08/australian_por...