I know this is an issue that arouses passions. As a dad, I know if anyone sexually abused my son, I'd want to subject them to a long, slow and painful death. Or, reminding myself of my opposition to the death penalty, within an inch of their mortal soul.
But...
There's a difference between obscenity and pornography. One's illegal all the time. Some, it depends on where you live. (Although less and less so). Child porn is always obscene, therefore illegal. This VCP ruling is actually of staggering importance, and I'm not sure exactly what to think of it. Yet.
But I think it's a bit of a red herring. The slippery slope I see referenced here has a plateau to it. It's called the SLAPS test(for social, literary, artistic, political or scientific. A little First Amendment law humor...) Established by the court in the Hustler case against Jerry Falwell (*if memory serves*) it essentially states that anything that can pass the SLAPS test is not considered obscene material.
This is the result of the famous "I can't define obscenity, but I know it when I see it" declaration. There's no universally accepted definition of obscenity.
But there are a few things to be mindful of:
1) Slinky's example above is accurate; there are very aggressive postal inspectors and LE types who have wrongly prosecuted people based on weak set-ups as he described.
2) Ever open an email to be shocked by its contents? You too could be guilty of violating obscenity rules as currently written. Possession, in this area, is 10/10ths of the law.
I take the libertarian side in this. Strongly. I think we use anti-child porn laws to excuse real laziness on society's part.
It may be easier and safer than ever, given the Internet, to prosecute child pornographers. We just have to devote the resources to doing it. I'm with JC here; I think some kind of licensing of dangerous material (i.e. VCP) is appropriate. More appropriate would be tracking down the producers of real child porn and throwing the book at them. (i.e., years and years in jail, with a big sign on their backs telling all their fellow inmates what they're in jail for.)
Lolita is a great book and, even though it contains nary a dirty word, it does deal in an artistic way with a genuinely important topic -- lust. I think everyone ought to have to read it. It makes the argument for me that banning thoughts, art, pixar animations and any other kind of artistic expression is a waste of time and resources.