Hi Daniel,
Interesting report, about WD tagging I would also mention Denny's qLabel:
Regarding cost-efficient tagging options, there are automated tagging/entity extraction methods like DBpedia Spotlight, which can be further improved by using them together with human supervision/custody around an established online community.
I'm also unsure about the mark-up of semantically unaware publications, since marking-up requires access to an editable version of the text and that requires an open license. Semantic annotations don't seem to suffer of that problem and there are several open source initiatives in development.
Cheers,
Micru