Data-oriented middleware has always been one of the most important, and troublesome areas of interoperability. When XML came around, there were very high hopes for improved data exchange among diverse systems. An interesting effort looking to spur things along is the Data Documentation Initiative.
The Data Documentation Initiative is an international effort to establish a standard for technical documentation describing social science data. DDI has received external support from the National Science Foundation and Health Canada.
A DDI 3.0 release candidate is now available. The group’s work may influence the course of some IT-oriented data documentation efforts.
More info available at Data Documentation Alliance