Wired writes about how YouTube Bans Anti-Creationist Group Following DMCA Claim. This ought to become an example of the chilling effects of DMCA and similar recent laws.
Basically a creationist group sent a DMCA request to YouTube after the Rational Response Squad picked apart a few of their claims. This in itself is nothing new, the Foresight Institute got into a hot discussion with Scientific American back in the days when they wrote a line-by-line rebuttal of an anti-nanotech article. But in this case not only fair use would apply, but also claim at the creationist website that none of the materials was copyrighted since they wanted them spread (but not criticized).
Except that that no-copyright clause just went down the memory hole - after people reacted to this inconsistency. A YouTube employee looking today would get a very different view than the true state.
In this case this will hardly matter. It is too little too late, and will likely add fuel to the fire. But had this not been a cause celebree among atheist bloggers, who had stored files proving the change? It is already very easy to get a website or movie clip removed by claiming copyright regardless of actual merit. Often the decision is made by people with no schooling in IP law and few resources to examine the claim. This makes copyright claims very effective means of stifling criticism. Given the transient and changeable nature of the web it does not seem too hard to retroactively shore up false or anti-fair use claims.
The lesson of this is clear: we need better wayback machines but also to store what we browse and use individually. Ideally this stored material should be hard to manipulate, making it better evidence in a court case. Given the growth of storage space it is not too absurd to have a cache that stores everything, possibly timestamped and authentificated using trusted computing (hey! it can be used for at least *one* other benign purpose beside checking that P2P or internet gambling client software is not forged :-) Then we need to figure out how to make the response to takedown claims rational. That is going to be much harder.