"Today's one-way hypertext - the World Wide Web - is far too shallow. The Xanadu project foresaw world-wide hypertext and has always endeavored to create a much deeper system. The Web, however, took over with a very shallow structure. Our simple, but very different structure - for details see "The Xanadu Model" - allows -
- UNBREAKABLE LINKS.
- COPYRIGHT SIMPLIFICATION AND SOFTENING.
- ORIGIN CONNECTION.
- TWO-WAY LINKS.
- SIDE-SIDE INTERCOMPARISON.
- DEEP VERSION MANAGEMENT.
- INCREMENTAL PUBLISHING.
How can this be? Very simple, but very different."

If this is "simple", then it's a definition of "simple" from a parallel universe :-) But on the other hand some of these concepts have been kicking around the blogosphere recently. For example, two-way links... this from Matt's notes:

"the web lacks:
- 2 way links
- link overlays that anyone can create

the web is just the file system online. directories with one-way jumplinks"

Two-way links in the blog world means comments, trackback, referrers, Technorati - all the things that provide information on who is linking to you or commenting on you. Nelson defines two-way links as: "anyone may publish connected comments to any page". So it's about connections, not just one-way via an HTML a href, but back and forth across the Web. Two-way links are about tracking conversations, following trails of information (to paraphrase Vannevar Bush). The Disenchanted website has an interesting article on this, called Ghosts of Xanadu:

"Cheap and democratic as it was, Berners-Lee's Web didn't have half the features Xanadu promised to, and two-way linking was one of them. Without a central server it couldn't be enforced, and to make authorship of pages as simple as possible - given the state of the art at the time - it had to be left out along with automatic attribution, micropayments, copyright management, unbreakable links, and most of Nelson's other ideas. But ten years later, a ghost of Xanadu is being recreated in the same style as the Web itself: quick, dirty, and cheap. Like Xanadu, it could have interesting implications for the way we structure knowledge."

By "quick, dirty, and cheap" Disenchanted may be referring to the weblog phenomonem, where tools such as Trackback, Technorati and Topic Exchange (amongst many others) are being bootstrapped into existence. All these tools, in the sum of the parts, are fulfilling Ted Nelson's vision of two-way links. Of course there's much more to Xanadu than two-way links. But by bootstrapping the current Web piece-by-piece, instead of trying to develop a grand mind-blowing concept like Xanadu, maybe that's the way to fulfil Ted Nelson's vision - even if it's not the exact system he has in mind.