Can we please, please separate the issue of whether this is an indecent photograph of a child, from the issue of whether it should be censored on the internet?
I think that the photo indecently depicts a naked, underaged girl in a sexually provocative position. And, while I wouldn't classify it as pornographic myself, I am not surprised in the least that some people think it is child porn. I don't think that the photograph should have been taken, and I think the band and record label should have thought more carefully about putting it on their front cover.
However, I do NOT support the UK Government and ISPs from censoring the wikipedia article, or any other replications of the image on e.g. Amazon or Play.com. I support censoring genuine child pornography websites, and arresting those involved. But Wikipedia is clearly not a child porn website, and the image is provided for genuine educational purposes.
So lets focus on one thing at a time, eh?
I would support censorship of websites and tolerate the downsides, if it were actually feasible to prevent people from accessing child pornography. But it's not, unless you ban and persecute the use of proxies, encrypted IRC/IM connections, anonymity networks, etc - impossible to enforce without removing all privacy during internet communications. That's a price i am not willing to pay, just like i am not ready to allow anyone to read my (snail) mail or wiretap my phone calls.
It would surprise me if there actually were (m)any child porn websites on the open WWW, which could be censored with such crude methods as the OP describes. As it would be trvial to find the server location and monitor traffic to them, they would be very easy to lock down so censorship wouldn't be required. (Unless the country hosting the server allows child porn - does any? Even then, you could monitor connections to the server and use it to identify pedophiles)
I used to run a
TOR relay and eventually got curious about the hidden services that are hosted within the network. As i explored, i found, among others, several sites dedicated to child pornography and child pornography being the most popular subject of discussion on the hidden message boards i came across.
Non of these hidden sites can be blocked or locked down easily, even if you try to prevent access to the entire network.
The only way to get them is by social engineering or by examining the server responses for hints on a case by case basis.
This is just anecdotal evidence, of course, but it does show that some pedophiles know how to protect themselves from identification.
So in a nutshell, i view internet censorship as a tool of little value in the persecution of child pornography.
