Eric Lease Morgan and LiAM have released Linked Archival Metadata: A Guidebook (Version 0.99).
Here's an excerpt:
Linked data is a process for embedding the descriptive information of archives into the very fabric of the Web. By transforming archival description into linked data, an archivist will enable other people as well as computers to read and use their archival description, even if the others are not a part of the archival community. The process goes both ways. Linked data also empowers archivists to use and incorporate the information of other linked data providers into their local description. This enables archivists to make their descriptions more thorough, more complete, and more value-added. For example, archival collections could be automatically supplemented with geographic coordinates in order to make maps, images of people or additional biographic descriptions to make collections come alive, or bibliographies for further reading.