There's an interesting scheme that started in America... Circle of Friends, IIRC... that basically supported paedophiles leaving prison by providing a support network of people who would engage with them regularly, doing normal stuff like going out for lunch or going to the cinema. The logic was that if you release someone into exactly the same environment, without "normal" people to interact with, they'll fall into the same patterns. Obviously the "circle" of people who support them receive counselling themselves, and they also report any indication of potential re-offending - like if they see the paedophile talking to children. But the interesting thing with this scheme was that it got re-offending rates down from something like 90% to 10% (approx. - can't remember the exact figures, but they were in that league of impressive).
What that suggests to me is that if we sit down and look at the problem calmly, there's the potential to find solutions that work (at least for certain classes of offender). And if the key thing is protecting children, and if we take it as given that we aren't about to execute every sex offender, then that would seem like a good idea.