No.

why?

You might as well lock up Counterstrike players for potential murder and assault.  There's no victim, you're punishing thought crimes.

What about a man that is not on second life or any online media but who sits in his house and watches little girls in his neighbourhood? Should he be locked up too? What about a female teacher who know the little boys in her class like her and get a kick out of going pantyless (all be it unknow to everyone else) and touching the little boys on their hand ever so lightly? Should we fire her from her job and send her for rehabilitation?

It is well and good to want to protect children from sadists and pedofiles, its another thing to try to control a persons thoughts.... 

If they want to control peoples thoughts.... that is what religion is for...

Otherwise... all they can do is shut down inappropriate characters as they spring up.... simple. Do something in my world that I dont like... shut you down.