Set them up how?
Assuming it was Karl Rove or Hillary Clinton (ie someone who wants Kerry to lose), handing heavily booby trapped documents to a major news organization, even through proxies, is very dangerous. I highly doubt this.
Assuming that it was someone who wanted Kerry to win, then it illustrates just how blindly desperate they are becoming. I say this of both the document makers and CBS. This is by far the more likely explination, but it's also a very pathetic and disturbing milestone.
It had to be someone that was pretty sure Danny would run with them, and not bother to have them authenticated.
But, my guess is that CBS/Dan Rather just do not understand the power of the "new media", and that they would be taken down in less than 14 hours.
They are probably still spinning trying to figure out how the "common people" could take them down.