We should probably also link to Nelson's response [1] to what he termed a hatchet job.
That said, it seems to me that the response is fairly nit-picky. You'd think that the Xanadu guys could put together an unoptimized demo of what their vision was using modern tech to brute-force things that would have had to be finessed. I understand they did release a demo a number of years ago, but I could never get it to work.
That's an addendum to his letter to Wired http://web.archive.org/web/20001101230424/http://www2.educ.k... , which is where the weightier issues tend are set out, by and large. Some of the complaints are indeed small, but I'm sure Nelson would point out that there are quite a lot of them and they seem intended to make him look bad.
It's clear that there are indeed some serious issues with the Wired story. For example if you read point 3 of the Wired letter, "Transclusion Misstated", it's evident that Ted Nelson understood content-addressable networking long before eg. Bittorrent came about. Gary Wolf, though, apparently didn't quite get content-addressable networking even after researching Xanadu, meeting with Nelson himself, and writing a feature article about Xanadu for Wired; but he pronounced confidently about it in the article anyway.
I think the addendum you linked to is a refinement of the response I linked to. I haven't read the addendum thoroughly yet (I hadn't seen it before), but it seems to be much better than the one I cited. For one thing, he defers nit-picking in favour of going straight into the more important stuff.
The letter to Wired was the main response, the 'Errors in "The Curse of Xanadu"' document was the detailed addendum to that which (I'm 98% sure) was the target of the now-dead http://xanadu.net/wolfsbane link (yes).
That said, it seems to me that the response is fairly nit-picky. You'd think that the Xanadu guys could put together an unoptimized demo of what their vision was using modern tech to brute-force things that would have had to be finessed. I understand they did release a demo a number of years ago, but I could never get it to work.
[1] Errors in "The Curse of Xanadu," by Gary Wolf: http://web.archive.org/web/20001003011753/http://xanadu.com....