Henry Thompson, in a post to XML-dev, indicated that the XML Schema Working Group will soon present solutions to the question of document->schema linking and related problems.

The issue of whether a namespace URI should map directly to an XML schema has caused much excitement in recent times, having raised its head during the debate over XHTML.

Thompson promises a "detailed set of facilities for instance-schema linking, schema aggregation and validation for documents with multiple namespaces" in the next XML Schema working draft. He adds that the "pros and cons of dereferencing namespace URIs as raised in this thread were very much part of our deliberations."