The tagging of information, particularly deep wells of structured data, is definitely the challenge for which XML provides a tool. But, just as the Web is much more than HTML, XML provides only a partial foundation for Internet maps. The meta-information are the features that make up the geography of an Internet map, the rivers and mountains that distinguish one area from another. Only when this raw material has been categorized will visually rich, dense, and perhaps even useful maps come into widespread use. Indeed, just as the Web succeeded because people actually used it, one of the keys to meta-information will be getting large amounts of real content tagged and organized.
Consensual hallucinations require considerable preparation.
Maps are a shared version of reality. Once the infrastructure to share reality is in place, maps will flourish. Until then, maps of the Internet will be cartographic fiction, the creative musings of poets rather than shared constructions of reality.