xlabel is a contrib module that implements alternative XPath support for new XML type (new data type added in Postgres 8.3). xlabel type is GiST-based implementation of prefix numbering scheme. The general concept is similar to ORDPATHs in MSSQL.
The xlabelproject is a PostgreSQL Community project that is a part of the pgFoundry.
The pgFoundry page for the project is at http://pgfoundry.org/projects/xlabel, where you can find downloads, documentation, bug reports, mailing lists, and a whole lot more.
