I am not going to comment on the politics of this, there is a lot of that going on already but on some of the technical issues. If you don't know what I am talking about Rory Cellan-Jones has a blog post on the subject.
- For a significant period of time, the block was on the page but not the image.
They seem to have fixed this now, but when the story first broke and for most of the weekend if you looked at the page in a popular internet search engine's cache, which doesn't store images just links to them, there was the "offending" image in the RHS info box.
- The competence of some ISP network teams is in doubt.
In much about this story the use of the term "transparent proxy" has been used but there has also been reports that due to the use of the IWF blocker all traffic to Wikipedia was coming from limited IP addresses per affected ISP. Now this could all be a fault with the reporting of what was going on, but such proxies should be dealing with the traffic in such a way as not to provide such issues, hence transparent.
- The IWF suffers epic fail in understanding how Wikipedia and the internet works.
All they have really succeeded in doing is making more people look at this image, it doesn't even need any great skills to find, you just need to look at the page in the other languages it exists in until you find an unblocked one. They are in no way stopping cracked glass fetishists from getting their rocks off.
Child sexual abuse is not a nice thing, and this would be a better world if no child ever got harmed. However censorship is also not a nice thing and this would be a better world if it never happened either.