We've lost Dan Gillmor. Not literally, just historically. In the excellent wisdom of IT professionals interacting with a reader base without understanding why people read what they do, the San Jose Mercury News reorganized Dan's Web log archives as they transition to a new system. Rather than building a lookup table or a translation system that would allow old links to be directed seamlessly to the new system, they let them die, and die painfully (404). I've been dealing with this problem since 1996, at least, and never let old links rot and die. I wrote about this last April: Permanent URLs require advance design. But they're not impossible.
I can point to a news article written in Netscape World way back in 1996 about my migration techniques for Film.com. (Thanks to the Internet Archive's Way Back Machine, I can point you to the article even though the archives of this magazine expired long ago.) It's not rocket science, folks.