Ted Nelson summarises the aims of Project Xanadu, and where it goes from here, in a recent (late 1999) article Xanalogical Media: Needed Now More Than Ever. A point raised is the important of linking to content rather than documents and how to do this; interestingly it's something the W3C are tackling with xml linking. It seems that TBL's vision of the semantic web brings us closer to Xanadu.