Michael Wacey argues inThe Semantic Organization: Knowing What You Know that corporations have a tremendous amount of stored information and are likely to be the early adoption point for semantic Web capabillities, similar to the ways in which corporations have proven to be the adopters for Web services and the underlying technologies (UDDI, WSDL, SOAP) initially designed for the Web at large.
I agree with his premise that Web-wide adoption of semantic tagging is unlikely at first and individual organizations offer better and easier proving grounds. However, my experience has been that government agencies have been the leaders in semantic and entity extraction; for reasons noted elsewhere, corporations have been slow on the uptake.
Some of the stumbling blocks appear to be lack of understanding of benefits by top management and the lack of automated and accurate means to "tag" content at scale and then manage it. Until these fundamental sticking points are greased, we are likely to continue to see the leadership in promoting semantic Web capabilties by government entities where lives and national security are at stake.