Bob's blog and some relevant entries:
Some companies in the publisher/library metadata business: Ingram Book Company's ipage (clever name, right?), GiantChair, Bowker, Nielsen BookData
Rachel Lovinger presentation There's no semantic web without content and data (slideshare)
Nimble Razofish report on publishing in the digital age
Some image metadata standards: EXIF, XMP, and Library of Congress MIX.
Some rights management standards for publishing: PRISM, ONIX, XACML, ODRL, CC REL, and ACAP.
OCLC (Online Computer Library Center)
TaxoCoP (Taxonomy Community of Practice) Yahoo group and mailing list
PPT presentation From ONIX to MARC and Back Again: New Frontiers in Metadata Creation at OCLC by the OCLC's Renee Register
Wikipedia page for Crosswalk (metadata)
W3C Library Linked Data Incubator Group
devX article Using RDFa with DITA and DocBook
TopQuadrant's SKOS-based Enterprise Vocabulary Management System